The independent variable is a variable that can be stood alone. So therefore, the independent variable would be how long it takes to parachute.
The central processing unit (CPU), also called a processor, is located inside the computer case on the motherboard. It is sometimes called the brain of the computer, and its job is to carry out commands.
Option D, Demography. I’ll go over why the other three options are wrong.
Ecology studies organisms and how they react to each other, not the age structures of cities!
Anthropology is the study of humans from the past, which doesn’t really have anything to do with the ages of people in a city.
Biology studies life and organisms, but doesn’t specifically cover ages of people in a city.
Demography, on the other hand, is the study of statistics of populations of humans. Obviously, this option is the correct option.
-T.B.
