Answer

` A - q; B - r ; C - s; - D-p`

Explanation

(a) `H-underset(O)underset(||)overset(OH)overset(|)(P^(+2))-underset(O)underset(||)overset(OH)overset(|)(P^(+2))-H`

c) `H-overset(OH)overset(|)underset(O)underset(||)(P^(+2))-overset(OH)overset(|)underset(O)underset(||)(P^(+4))-OH` d) `HO-overset(OH)overset(|)underset(O)underset(||)(P^(+4))-overset(OH)overset(|)underset(O)underset(||)(P^(+4))-OH`