Infertility is when a couple fails to conceive after

The correct option is 1 years of unprotected sex.

Infertility is a clinical condition defined by major global health organizations, including the World Health Organization (WHO) and the American Society for Reproductive Medicine (ASRM), as the failure to achieve a clinical pregnancy after 12 months (or 1 year) of regular, unprotected sexual intercourse.

This standard timeframe is determined based on the statistical probability of conception in healthy couples:
- Approximately 80% to 85% of couples conceive within the first 12 months of regular, unprotected sex.
- After one year of trying without success, the likelihood of conceiving naturally decreases significantly, which is why medical professionals recommend initiating fertility evaluations and treatment options at this point.