In Gottman's Research on Friendship Formation, What Differentiated Pairs of Children

In Gottman's research on friendship formation, what differentiated pairs of children who became friends from those who did not?

A) Children who became friends were of higher intelligence.
B) Children who became friends were more sociable.
C) Children who became friends showed greater communication clarity and were more skilled at resolving conflict.
D) Children who became friends tended to talk little about themselves or the activities that interested them.