All of the Following Observations About Becoming a Sibling Have

All of the following observations about becoming a sibling have been supported except

A) it is unusual for firstborn children to experience the birth of a sibling negatively
B) children younger than 18 months tend to show little disruption and negativity in comparison with preschool-age children
C) preschool-age boys tend to react more negatively than preschool-age girls to the birth of a younger sibling
D) firstborn children respond more positively to the birth of a sibling if they and their friends engage in fantasy and pretend play that involves sibling-related themes