In Societies Where the Leaders Are Chosen, We Need More

In societies where the leaders are chosen, we need more research to understand why some kinds of people are chosen over others. Why would this be helpful?

A) because we see differences in the personal qualities of leaders in different societies
B) because we can't see many differences as yet
C) because it had never been researched before
D) because leaders tend to be shorter and younger and it would be good to know why