The trait theory of group leadership says that​

A) After a person has led a group,there are still some things he or she can do to achieve more complete success.
B) There are certain roles that must be performed if a group is to be successful. 
C) There are certain qualities a person must have in order to become a successful leader.
D) ​Psychological aspects of leadership must be considered when selecting a leader.

The trait theory of group leadership suggests that there are certain qualities that an individual must possess in order to become an effective leader. This theory focuses on the individual characteristics of a leader such as personality, intelligence, and communication skills. It does not necessarily address specific roles or behaviors that must be performed by a leader, nor does it focus on post-leadership actions. It also doesn't specifically address psychological aspects of leadership.