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 $NH_3$ along with a solid residue. The solid residue give violet colour with alkaline copper sulphate solution. The compound is :

Question

( A ) $CH_3CONH_2$
( B ) $CH_3CH_2CONH_2$
( C ) $CH_3NCO$
( D ) $(NH_2)_2CO$