In man, identical twins occur when
-
A.
An ovum is fertilized by a sperm and then divide into two, each forming a separate embryo -
B.
an ovum fertilized by two sperms and then divides into two, each forming an embryo -
C.
two ova are fertilized at the same tine each forming an embryo -
D.
two ova are fertilized by a single sperm each forming an embryo after fertilization -
E.
one ovum first divides into two and each half is fertilized by a sperm before developing into an embryo