Which one of the following statements with regard to embryonic development in humans is correct?

• A
  Cleavage divisions bring about considerable increase in the mass of protoplasm
• B
  In the second cleavage division,one of the two blastomeres usually divides a little sooner than the second
• C
  With more cleavage divisions,the resultant blastomeres become larger and larger
• D
  Cleavage division results in a hollow ball of cells called morula