Three letter groups with step of four – UGC NET Question

Starting letters C(3), G(7), K(11), O(15) increase by +4. Next start is S(19), so the block is STU.

Option A:
Option A is correct because S is +4 from O and T,U follow consecutively.

Option B:
Option B starts at R(18), which is +3 from O, not +4.

Option C:
Option C starts at V(22), which is +7 from O, not +4.

Option D:
Option D starts at N(14), which goes backward and breaks the progression.