Which of the following parts of the historian's argument is a piece of historical evidence?
a. "based on these points, he argues that the french revolution produced far more negative outcomes than positive ones."
b. "in his opinion, it is morally wrong for any political movement to use violence to achieve its goals."
c. "he points to the execution of the french royalty and the european wars the revolutionaries launched following their victory to support this point."
d. "he notes that, following the revolution, a rash of violence swept over france."