Which of the following is the reason why a majority of adults aged 20-34, and a sizable portion of adults overall, remain never married in the United States?

• A. A widespread preference among young adults for serial casual relationships rather than any long‑term commitment, with many prioritizing short‑term dating, delaying cohabitation, emphasizing personal freedom, and avoiding traditional marriage expectations.
• B. Primarily declining fertility and health concerns among young adults, including reduced desire for biological parenting, delayed childbearing, perceived infertility risks, and increasing chronic health issues that purportedly lower interest in entering marriage.
• C. Solely the increasing legal costs and bureaucratic hurdles to obtaining a marriage license, including rising fees, complex paperwork, varying statewide requirements, long waiting periods, and administrative barriers that make formal marriage difficult.
• D. Multiple interacting causes, including delayed marriage due to education and career goals; economic constraints (debt, housing); greater cohabitation; changing cultural norms; contraceptive access; female economic independence; concerns about divorce; and demographic partner imbalances.

Answer: (D)