Fertilization in humans is practically feasible only if:
the sperms are transported into cervix within 48 hrs of the release of an ovum in a uterus.
the sperms are transported into the vagina just after the release of the ovum in the fallopian tube.
the ovum and sperms are transported simultaneously to ampullary – isthmic junction of the fallopian tube.
the ovum and sperms are transported simultaneously to ampullary – isthmic junction of the cervix.