Directions: There is some relationship between the two pair of letters on the left of the sign (::). The same relationship exists between the two terms on the right of which one is missing. Find the missing one from the given alternatives.

Cgk : dHl : : ? : rVz

In the pair Cgk : dHl, each letter shifts by +1 position in the alphabet: C→d (c→d, +1), g→H (g→h, +1), k→l (k→l, +1). The case pattern follows lowercase→lowercase→lowercase on the left and lowercase→uppercase→lowercase on the right. Applying the reverse transformation to rVz: r→q (-1), V→u (-1), z→y (-1). The case pattern should be lowercase→uppercase→lowercase, giving 'quY'.