With Regard to the Typical Composition of Peer Groups in Middle

With regard to the typical composition of peer groups in middle childhood,which of the following statements is correct?

A) Peer groups are usually all boys or all girls,because children of the same sex have common interests.
B) Peer groups usually consist of both girls and boys,because at this age youngsters have not yet become self-conscious about differences between the sexes,and girls and boys are still at about the same level of maturity.
C) Because peer groups are generally neighborhood-based,ages of members usually differ by three to four years.
D) Because peer groups are almost always school-based,members are almost always the same age.