Question

why was homer plessy arrested?
he said his rights had been violated.
he was clearly of mixed heritage.
he refused to give his seat to a white person.
he sat down in a trains whites-only car.

Explanation:

Homer Plessy was arrested for sitting in a train car designated for white people only, as part of a test case against the "separate but equal" doctrine. The option "He said his rights had been violated" is about his claim after arrest, "He was clearly of mixed heritage" is his background not the arrest reason, and "He refused to give his seat to a white person" is not accurate (he sat in the whites - only car, not refused to give a seat). The correct reason for his arrest is sitting in the whites - only car.

Answer:

D. He sat down in a train's whites - only car.