In the carbon cycle of fusion :

Question

( A ) four $_1H^2$ fuse to form $_2He^4$ and two neutrons
( B ) four $_1H^1$ fuse to form $_2He^4$ and two positrons
( C ) two $_1H^2$ fuse to form $_2He^4$
( D ) four $_1H^1$ fuse to form $_2He^4$ and two electrons