During a Scheduled Well-Child Visit the Mother of a 3-Year-Old

During a scheduled well-child visit the mother of a 3-year-old states, "My child masturbates in the bathtub, and it is very upsetting to me." Which response by the nurse is most appropriate?

A) "Tell your child not to do that. It is dirty."
B) "Masturbation is normal. Just tell your child that it is a private thing to do."
C) "Encourage your child's self-expression."
D) "Children don't usually do that until they are teenagers."