In both DNA and RNA heterocyclic base and phosphate ester linkages are at

Question

$\begin {array} {1 1} (A)\;\text{$C_S'$ and $C_1'$ respectively of the sugar molecule}\\ (B)\;\text{$C_1'$ and $C_S'$ respectively of the sugar molecule} \\ (C)\;\text{$C_2'$ and $C_S'$ respectively of the sugar molecule}\\ (D)\;\text{$C_5'$ and $C_2'$ respectively of the sugar molecule } \end {array}$