When you accept someone else's ideas because you think she must know better than you, it is called:
a. normative social influence
b. informal social influence
c. attribution
d. fundamental social influence

B. Informational Social Influence

Explanation:

In psychology, Informational Social Influence (or Social Proof) is a phenomenon that occurs when we change our ideas or behaviors to someone else's ideas or behaviors because we believe that they must know better. It is driven for our need to be right and it usually happens when we do not know what to do, are uncertain of our ability to do or be right, or trust other's knowledge or opinions more than ours.