You will be given a definition of a task first, then some input of the task.
In this task you will be given a text passage from a trivia quiz. You should choose the category this question belongs to from these categories: History, Science, Social Science, Fine Arts, Literature. You can only choose one category, so if in doubt, please choose the closest match.

In 1921, its functional significance was determined. Otto Loewi took fluid from a frog's heart, whose contractions had been slowed, and let it perfuse a second, unstimulated heart, slowing its beating as well. Mimicked by nicotine, this neurotransmitter plays a major role in memory as well as muscle control. FTP, name this primary neurotransmitter between neurons and muscles.
Output:
Science