'A # B' means 'A is the daughter of B'.
'A % B' means 'A is the husband of B'.
'A & B' means 'A is brother of B'.
'A @ B' means 'A is sister of B'.

If S#P%Q@T&V%X, then how is S related to X?

Let's break down the relationships from left to right:
S#P⟹ S is the daughter of P.

P%Q⟹ P is the husband of Q (So, Q is the mother of S).

Q@T⟹ Q is the sister of T.

T&V⟹ T is the brother of V (So Q, T, and V are siblings).

V%X⟹ V is the husband of X (So, X is V's wife).

Let's establish the relationship from X's perspective to S:

X's husband is V.

V's sister is Q.

Q's daughter is S.
So S is the daughter of X's husband's sister (Husband's sister's daughter).

This matches Option A.