Why Was the Trait Theory of Leadership Mainly Unsuccessful

Why was the trait theory of leadership mainly unsuccessful?

A) Researchers were not able to identify a set of traits that always differentiated a leader from a nonleader.
B) Organizations found the trait theory of leadership too expensive to implement due to the high costs of testing potential leaders.
C) Research has shown that leadership traits are gender specific, so the process of choosing leaders based on traits is discriminatory.
D) Too much emphasis was placed on personality traits rather than physical traits, which have been found to successfully predict leadership.