Researchers Have Found That Couples Who Have Been Married for a Long

Researchers have found that couples who have been married for a long time have sex less often. What is likely the reason?

A) People who are married start out having sex more than unmarried couples but become bored with each other.
B) People who have been married longer are older and the decline in sex is age related.
C) People who are married longer are not as committed to the relationship as unmarried people.
D) People who are married always have a lower frequency of sex than unmarried people.