​Which of the Following Statements Is FALSE

​Which of the following statements is FALSE?

A) Sex play with friends of the same sex or other sex is a common part of growing up for many children.
B) By the age of eight or nine, most boys and girls begin to play in gender-segregated groups.
C) Children of any age who display their genitals to other children should be seen by a mental health professional.
D) In the childhood years, both boys and girls engage in masturbation.