Select the letter-cluster that is related to the third letter-cluster in the same way as the second letter-cluster is related to the first letter-cluster.
EHQ : VSJ :: FCO : ?

Let's evaluate the relationship between EHQ and VSJ:
Opposite letters pairs in the English alphabet sum up to 27 in positional value.

Opposite of E(5) is V(22) →5+22=27

Opposite of H(8) is S(19) →8+19=27

Opposite of Q(17) is J(10) →17+10=27

So, the second cluster contains the exact opposite pairs of the first cluster.

Applying this pattern to FCO:

Opposite of F(6) is U(21)

Opposite of C(3) is X(24)

Opposite of O(15) is L(12)

Thus, the related cluster is UXL.