c. They continued to use their group estimates when retested alone one year later.
Explanation:
Public conformity occurs when an individual makes a decision or judgement about something as a result of external pressures around him/her and not because he/she believes that action is right. In public conformity, individuals pretend to agree with the group but personally disagrees. On the other hand, in private conformity, individuals decides on an action based on internal reasons.
If individuals continue to use their group estimates when retested alone one year later, it is an indication that the original estimate was based on private conformity and not public conformity. If it was based on public conformity, the individual would have changes his/her estimate since the group is no longer present to exercise pressure over his/her decision.
