Which of the following is correct w.r.t tapetum? 

a. It is the innermost nutritive layer 

b. Cells of the tapetum possess dense cytoplasm and generally have more than one nucleus.

c. The cells turn polyploid due to endomitosis.

d. It helps in degeneration of pollen kitt 

• A

   a and b

• B

  a, b and d

• C

  a, b and c

• D

  a, b, c and d