<prompt> Which of the following contraceptives can prevent a pregnancy when used alone after an act of unprotected intercourse?Copper IUCDProgesterone or Combined oral contraceptivesMifepristoneAll of these can work if used within 3 days of Unprotected Intercourse  <response>: Emergency contraceptives IUCD: Can prevent implantation up till 5th day of unprotected inter-course Progesterone only pill: LNG 1.5 mg :can reduce tubal motility , make endometrium Out of Phase for implantation of embryo Combined Pill: the Yuzpe regimen can prevent embryo implantation since the estrogen component makes the endometrium unreceptive. Mifepristone, Antiprogestin, RU 486, prevents implantation Ulipristal acetate: SPRM: Selective progesterone receptor modulator 