Final answer:
Scholarly inquiry into leadership became prolific in the 20th century due to a shift in perceptions of authority and an interest in understanding human psychology.
Step-by-step explanation:
Scholarly inquiry into leadership became prolific in the 20th century. After World War I, there was a shift in the perception of authority and a growing interest in understanding the psychology behind people's choices. This led to the rise of contemporary intellectual history, which focuses on the ideas that drive people's decision-making and the history of human thought.