In both DNA and RNA, heterocylic base and phosphate ester linkages are at :

Question

( A ) $C_1'$ and $C_5'$ respectively of the sugar molecule
( B ) $C_5'$ and $C_1'$ respectively of the sugar molecule
( C ) $C_2'$ and $C_5'$ respectively of the sugar molecule
( D ) $C_5'$ and $C_5'$ respectively of the sugar molecule