Extract the answer to the question from the following context. Question: Prior to his discovery what was the creator's main field of study? Context: Charles Babbage, an English mechanical engineer and polymath, originated the concept of a programmable computer. Considered the "father of the computer", he conceptualized and invented the first mechanical computer in the early 19th century. After working on his revolutionary difference engine, designed to aid in navigational calculations, in 1833 he realized that a much more general design, an Analytical Engine, was possible. The input of programs and data was to be provided to the machine via punched cards, a method being used at the time to direct mechanical looms such as the Jacquard loom. For output, the machine would have a printer, a curve plotter and a bell. The machine would also be able to punch numbers onto cards to be read in later. The Engine incorporated an arithmetic logic unit, control flow in the form of conditional branching and loops, and integrated memory, making it the first design for a general-purpose computer that could be described in modern terms as Turing-complete.
----
Answer: navigational calculations


Extract the answer to the question from the following context. Question: Who was Ludwika's husband's brother-in-law? Context: With his health further deteriorating, Chopin desired to have a family member with him. In June 1849 his sister Ludwika came to Paris with her husband and daughter, and in September, supported by a loan from Jane Stirling, he took an apartment at Place Vendôme 12. After 15 October, when his condition took a marked turn for the worse, only a handful of his closest friends remained with him, although Viardot remarked sardonically that "all the grand Parisian ladies considered it de rigueur to faint in his room."
----
Answer: Chopin


Extract the answer to the question from the following context. Question: What did Mr. McVeigh build in 1995? Context: On April 19, 1995, the Alfred P. Murrah Federal Building was destroyed by a fertilizer bomb manufactured and detonated by Timothy McVeigh. The blast and catastrophic collapse killed 168 people and injured over 680. The blast shockwave destroyed or damaged 324 buildings within a 340-meter radius, destroyed or burned 86 cars, and shattered glass in 258 nearby buildings, causing at least an estimated $652 million worth of damage. The main suspect- Timothy McVeigh, was executed by lethal injection on June 11, 2001. It was the deadliest single domestic terrorist attack in US history, prior to 9/11.
----
Answer:
a fertilizer bomb