Our sleep cycles typically last usually 90 to 110 minutes on average.
Most sand dunes are created by deposition by Wind.
Answer:
I believe the answer is A
Explanation:
The other reasons would not give enough reason for competition between populations.
The correct answer is pretest and posttest .
A pretest/posttest experiment is an experiment that includes double measurements at multiple points in time. In this kind of test, measurements (measurement of dependent variable) are taken both before and after a treatment.
