What Did Main and Weston Conclude from Their Research Regarding

What did Main and Weston conclude from their research regarding the role of mothers and fathers in an infant's attachment and social responsiveness?

A) As long as the child was securely attached to the mother, quality of attachment to the father had little impact on social responsiveness.
B) Children who were securely attached to the father but not to the mother were less socially responsive.
C) Children who were securely attached to both parents were the most socially responsive.
D) Children who were securely attached to the mother but not to the father were less socially responsive.