What Makes It Difficult to Interpret the Research on the Link

Multiple Choice

What makes it difficult to interpret the research on the link between marriage and happiness?

A) Much of the research is correlational and also involves indirect links between marriage and happiness.
B) Being married automatically puts people at risk for health problems which make people unhappy.
C) Husbands and wives serve as social support for each other, which can be draining and actually make you less happy.
D) There are confounding features, like the fact that many surveys take place right after people get married and are still in the "honeymoon period."