According to the Ethological Viewpoint, Why Do Stranger Anxiety and Separation

According to the ethological viewpoint, why do stranger anxiety and separation anxiety become less intense during the second year?

A) Children increase their use of the attachment figure as a secure base to explore novel things and people.
B) Children have had many opportunities by then to adapt to being separated.
C) Children have gained the cognitive maturity by then to recognize that the parent will return.
D) Children have developed more stable schemes for the faces of strangers and familiar companions.