What Did Michael Rutter Find in the Study of the Association

What did Michael Rutter find in the study of the association between family adversity and externalizing disorders?

A) There were no externalizing problems if there were no family problems.
B) There was no association between family problems and externalizing disorders.
C) The presence of one adversity factor was associated with a much higher rate of externalizing disorders.
D) The presence of two adversity factors was associated with a much higher rate of externalizing disorders.