Earlier Studies of Cohabitation Suggested That Living Together Before Marriage

Earlier studies of cohabitation suggested that living together before marriage affects the quality of the marital relationship for the worse.According to the text,what is one reason for questioning this conclusion?

A) These studies lumped together homosexual and heterosexual cohabitors.
B) Cohabiting couples develop problem-solving skills prior to marriage.
C) Premarital sex and cohabitation have become part of normal courtship.
D) Couples who separated before marriage weren't included in studies.