One of Albert Bandura's Most Important Contributions to Our Understanding

One of Albert Bandura's most important contributions to our understanding of child development is his demonstration that:

A) children are more likely to perform a behaviour for which they have observed others being rewarded.
B) there are two kinds of conditioning, operant and respondent.
C) social behaviour is closely tied to the evolutionary history of the species.
D) children do not refrain from exhibiting behaviours for which they have seen others punished.