Suppose You Collect Data About Child Abuse and Find That

Suppose you collect data about child abuse and find that mothers who have their first child before age 18 are more likely to be abusive than mothers who are older. However, you also note that young mothers are also more likely to be poor and have less access to prenatal care. Therefore, you cannot draw conclusions about maternal age and child abuse. The reason you cannot draw this conclusion is because your study involved:

A) a sequential-cohort design
B) a nonrandom sample
C) a nonrepresentative sample
D) confounding