A nucleus $_n^m{X}$ emits one α particle and two β– particles. The resulting nucleus is :

Question

( A ) $_{n}^{m-4} {X}$
( B ) $_{n-4}^{m-6} {Z}$
( C ) $_{n-2}^{m-4} {Y}$
( D ) $^{m-6} _{n}{Z}$