Identical twins are produced under one of the following conditions
A. two ova fertilized at the same time by the sperm B. one ovum fertilized divides to give two embryos C. two ova fertilized by one sperm D. one ovum fertilized by two sperms
Correct Answer: B
Explanation
Occasionally, the cells of a (two - celled) embryo separate, and each cell develops into a complete organism. Sometimes, the inner cell mass subdivides, forming two groups of cells, each of which develops independently. Because these cells have identical set of genes, the individuals formed are exactly alike - monozygotic, or identical twins. That is one ovum fertilized divides to give two identical embryo.