Question

Following on the successful activism of Cesar Chavez, Mexican American youths began to refer to themselves as

Answer 1

The correct answer is C. Chicanos.

"Chicano" was originally a pejorative (negative) term for Mexican Americans, especially the ones with an immigrant backgound.

Within the Mexican Americans there was a need for a new identity, and a feeling (both from within and from outside) that they were different both from the Mexican and from other Americans.
This identity, along with a fight for better fighters' rights, was at the heart of the Chicano Movement, which began in the 1940s.  Cesar Chavez was an important activist for this movement.