An organic compound having molecular mass 60 is found to contain C=20%, H=6.67% and N=46.67% while rest is oxygen. On heating it gives NH3 along with a solid residue. The solid residue give violet colour with alkaline CuSO4 , the compound is
(a) CH3 NCO
(b) CH3 CONH2
(c) (NH2)2 CO
(d) CH3 CH2 CONH2
