Three things that soil supplies to plants are _, _, and _.

The study of where things are 

Cpopulation density

The answer for your problem would be a. 7

Historians are researchers of the past or people who understand the history of people. with this field, they must possess qualities such as being unbiased, patient, efficient reader, has a knack for logic and critical thinking and reasoning, disciplined, open-minded, resourceful, with good analytical ability, good reasoning skills and problem solving!