Answer:
D
Step-by-step explanation:
The subject's in the line-judgment experiment conformed to the group standard when their judgments were observed by others but not when they were made in private. This tendency to conform in public demonstrates: normative social influence
Normative Social Influence i occurs when a person conforms in order to be accepted and belong to a group. They do this to avoid social rejection or being ridicule for not ‘fitting in.They feel it has some reward for conforming.
In this group they naturally comformed to the group when observed but not necessarily mean they do so in private.