Leadership Definitions Have Evolved During the 20^th Century in the Following

Leadership definitions have evolved during the 20^th century in the following way:

A) The trait approach remains the most popular approach over time.
B) A leader's power remains a key requirement for goal accomplishment.
C) Transformational leadership was formulated in the 1960s.
D) Focus on leadership effectiveness became prominent in the 1970s.
E) Leadership research peaked in the 1980s.