During Her Childhood,Holly Sees That Her Mother Disapproves of Same-Sex

During her childhood,Holly sees that her mother disapproves of same-sex marriages.Through watching her mother,Holly ends up adopting a similar viewpoint.This could be considered an example of what type of learning?

A) Observational learning
B) Operant conditioning
C) Classical conditioning
D) Observational learning, operant learning, and classical learning