Marie wants to know the most popular car for parents. She plans to survey the people entering the mall from 10:00 a.m. to 11:00 p.m. What can Marie do to make sure her survey is valid?
A. Marie's sample is valid.
B. Marie should also survey people entering the grocery stores.
C. Marie should make sure she surveys both the fathers and mothers.
D. Marie should make sure she surveys the children as well as the parents.
