<prompt> In the perspective of the busy life schedule in the modern society, the accepted minimum period of sexual cohabilitation resulting in no offspring for a couple to be declared infertile is:One yearOne and a half - yearTwo yearsThree years  <response>: If a couple fails to achieve pregnancy after one year of unprotected and regular intercourse, it is an indication to investigate the couple for infertility. Infertility: Primary : When no previous pregnancies have occurred. Secondary : When a prior pregnancy although not necessary although not necessary a live birth, has occurred. 