Fertilisation in humans is practically feasible only if

• A

  the ovum and sperms are transported simultaneously to ampullary-isthmic junction of the cervix

• B

  the sperms are transported into cervix within 48 hrs of release of ovum in uterus

• C

  the sperms are transported into vagina just after the release of ovum in Fallopian tube

• D

  the ovum and sperms are transported simultaneously to ampullary-isthmic junction of the Fallopian tube.