Please answer the following question: Given the following passage  "Wood is a heterogeneous, hygroscopic, cellular and anisotropic material. It consists of cells, and the cell walls are composed of micro-fibrils of cellulose (40% – 50%) and hemicellulose (15% – 25%) impregnated with lignin (15% – 30%).",  answer the following question. Note that the answer is present within the text.  Question: How much of a cell wall is lingnin?
A:
15% – 30%