The dramatic increase in the number of unmarried adults is largely a result of

A) the high costs involved in marriages.
B) the greater availability of birth control measures.
C) men and women marrying later.
D) a decline in morality in society as a whole.

Over the last few decades, the trend of marrying later in life has become increasingly common among both men and women. This has led to a rise in the number of unmarried adults, as they delay marriage in favour of pursuing careers, education, or personal goals before settling down. The other options - high costs of marriages, greater availability of birth control measures, and decline in morality in society - cannot fully explain the significant increase in unmarried adults.