Final answer:
The Scopes Monkey Trial of 1925 revolved around the theory of evolution, which high school teacher John Scopes was accused of teaching, in violation of Tennessee's Butler Act.
Step-by-step explanation:
The theory that was on trial during the Scopes Monkey Trial was the theory of evolution. This historic case from 1925 centered around John Scopes, a high school teacher in Dayton, Tennessee, who was accused of violating the Butler Act, which prohibited the teaching of any evolutionary theory that contradicted the biblical story of Creation.
The trial not only put Scopes in the hot seat but also became a national spectacle reflecting the intense conflict between modernist and fundamentalist perspectives in American society.
The prosecution was led by William Jennings Bryan, a famous conservative Christian and three-time presidential candidate. The defense was handled by Clarence Darrow, a prominent lawyer known for his agnostic views. The trial underscored the cultural tension of the era, pitting science and academic freedom against religious beliefs and the perceived sanctity of traditional values.