A substantial amount of research on toddlers' relations with siblings has focused on how they respond ____.

Question

Quizplus · Accepted Answer

The question is asking about research on toddlers' relations with siblings, and specifically mentions the birth of a younger sibling as a potential focus. Therefore, choice C (to the birth of a younger sibling) is the best answer. While research on twins or different gender siblings is certainly possible, the question is more specifically asking about the arrival of a new sibling.

A Substantial Amount of Research on Toddlers' Relations with Siblings