Last Year,Martina Was in Love with Robert,but They Eventually Broke

Multiple Choice

Last year,Martina was in love with Robert,but they eventually broke up.Today in the mall,Martina smells someone wearing the same cologne that Robert always wore.She is immediately filled with positive feelings,which is most likely due to

A) stimulus generalization.
B) stimulus discrimination.
C) second-order conditioning.
D) spontaneous recovery.