Please answer the following question: Information:  - Inflammation (from Latin "inflammatio") is part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or irritants, and is a protective response involving immune cells, blood vessels, and molecular mediators. The function of inflammation is to eliminate the initial cause of cell injury, clear out necrotic cells and tissues damaged from the original insult and the inflammatory process, and to initiate tissue repair.  - Eicosapentaenoic acid (EPA; also icosapentaenoic acid) is an omega-3 fatty acid. In physiological literature, it is given the name 20:5(n-3). It also has the trivial name timnodonic acid. In chemical structure, EPA is a carboxylic acid with a 20-carbon chain and five "cis" double bonds; the first double bond is located at the third carbon from the omega end.  - The blood vessels are the part of the circulatory system that transports blood throughout the human body. There are three major types of blood vessels: the arteries, which carry the blood away from the heart; the capillaries, which enable the actual exchange of water and chemicals between the blood and the tissues; and the veins, which carry blood from the capillaries back toward the heart. The word "vascular", meaning relating to the blood vessels, is derived from the Latin "vas", meaning vessel. A few structures (such as cartilage and the lens of the eye) do not contain blood vessels and are labeled.  - Eicosanoids are signaling molecules made by the enzymatic or non-enzymatic oxidation of arachidonic acid or other polyunsaturated fatty acids (PUFAs) that are, like arachidonic acid, 20 carbon units in length. They are a sub-category of oxylipins, i.e. oxidized fatty acids of diverse carbon units in length but are further distinguished from other oxylipins by their overwhelming importance as cell signaling molecules. Eicosanoids function in diverse physiological and pathological systems including those: mounting or inhibiting inflammation, allergy, fever and other immune responses; influencing the abortion of pregnancy and normal childbirth; contributing to the perception of pain; regulating cell growth; controlling blood pressure; and modulating the regional flow of blood to tissues. In performing these tasks, eicosanoids most often act as autocrine signaling agents to impact their cells of origin or as paracrine signaling agents to impact cells near to their cells of origin. However, they can also act as endocrine agents to control the function of distant cells.  - Enzymes are macromolecular biological catalysts. Enzymes accelerate, or catalyze, chemical reactions. The molecules at the beginning of the process upon which enzymes may act are called substrates and the enzyme converts these into different molecules, called products. Almost all metabolic processes in the cell need enzymes in order to occur at rates fast enough to sustain life. The set of enzymes made in a cell determines which metabolic pathways occur in that cell. The study of enzymes is called "enzymology".  - Arachidonate 5-lipoxygenase, also known as ALOX5, 5-lipoxygenase, 5-LOX, or 5-LO, is a non-heme iron-containing enzyme (EC 1.13.11.34) that in humans is encoded by the "ALOX5" gene. Arachidonate 5-lipoxygenase is a member of the lipoxygenase family of enzymes. It transforms EFA substrates into leukotrienes as well as a wide range of other biologically active products. ALOX5 is a current target for pharmaceutical intervention in a number of diseases.  - Leukotriene B4 is a leukotriene involved in inflammation . It is produced from leukocytes in response to inflammatory mediators and is able to induce the adhesion and activation of leukocytes on the endothelium , allowing them to bind to and cross it into the tissue . In neutrophils , it is also a potent chemoattractant , and is able to induce the formation of reactive oxygen species and the release of lysosomal enzymes by these cells . It is synthesized by leukotriene - A4 hydrolase from leukotriene A4 .  - Essential fatty acids, or EFAs, are fatty acids that humans and other animals must ingest because the body requires them for good health but cannot synthesize them.  - Latin (Latin: ) is a classical language belonging to the Italic branch of the Indo-European languages. The Latin alphabet is derived from the Etruscan and Greek alphabets.  - Leukotrienes are a family of eicosanoid inflammatory mediators produced in leukocytes by the oxidation of arachidonic acid (AA) and the essential fatty acid eicosapentaenoic acid (EPA) by the enzyme arachidonate 5-lipoxygenase.  - Arachidonic acid (AA, sometimes ARA) is a polyunsaturated omega-6 fatty acid 20:4(-6). It is structurally related to the saturated arachidic acid found in Cupuaçu butter ("L. arachis"  peanut).    After reading the paragraphs above, we are interested in knowing the entity with which 'leukotriene b4' exhibits the relationship of 'has part'. Find the answer from the choices below.  Choices: - a  - blood  - carbon  - cause  - cell  - family  - function  - human  - iron  - l  - language  - length  - lo  - member  - must  - n  - omega  - part  - peanut  - water  - word  - ω
A:
carbon