All of the Following Have Been Found in Studies of Siblings

All of the following have been found in studies of siblings except

A) older siblings rarely serve as their younger sibling's secure base for exploration
B) siblings typically play complementary roles, such as leader and follower
C) older siblings are more likely to direct positive behaviors toward their young sibling if their mother refers to the younger sibling's emotions or actions
D) sibling relationships change from nearly vertical in early childhood to nearly horizontal by the end of adolescence