Which Statement Provides an Example of the Manner in Which

Which statement provides an example of the manner in which children contribute to their own environment by regulating their own behaviour?

A) Children who are better able to control their negative emotions have more successful peer relations than do other children.
B) Children who are faster runners are more likely to participate in organized sports.
C) Children whose parents' discipline involves reasoning are more likely to develop a strong conscience than are other children.
D) Children who are twins are more similar in intelligence than children who are non-twin siblings.