Increasing length groups with growing gaps – UGC NET Question

Lengths increase 2,3,4,5 so next length is 6. Starting letters A(1), C(3), F(6), J(10) have gaps +2,+3,+4 so next gap is +5 → O(15). Six consecutive letters from O are OPQRST.

Option A:
Option A starts at L, not O, so it fails the starting-letter rule.

Option B:
Option B starts at M, not O, so it fails the starting-letter rule.

Option C:
Option C is correct because it starts at O and has exactly 6 consecutive letters.

Option D:
Option D starts at Q, not O, so it skips the required start.