In a Study About the Postpartum Habits of Mothers, What

In a study about the postpartum habits of mothers, what should be kept in mind regarding determining sample size?

A) The sample size needs to include enough women to merit publication in a medical journal.
B) The mothers must sign consent forms that include their newborn infants prior to the study.
C) Researchers must be careful to avoid accusations of bias by choosing only postpartum females.
D) The sample should be representative of the target population of women for results to be valid.