SSC CGL 2025 Tier-I · 15 September 2025, Shift 3 · General Intelligence and Reasoning · Question 5 of 100

We transcribed this text from the pictures on a candidate's response sheet for this shift; the answer is the key SSC colour-marked on that sheet. Solution last reviewed 11 September 2026.

Where this paper and its answers come from

SSC does not publish CGL question papers or a public answer key. From 2025 the candidate response sheet prints every question and option as a picture, so the text here is transcribed from those pictures for this shift and checked against them independently; where the layout carries meaning, the picture is shown as well. Each answer is the key SSC colour-marked on that sheet. SSC released a tentative key for challenge and later its final one, both only to candidates behind a login, and the sheet does not say which of the two it carries. The solutions are written by UnlockIAS.

Select the letter-cluster from among the given options that can replace the question mark (?) in the following series. MNO, OPQ, QRS, ?

(a)RST
(b)RSP
(c)STU
(d)TUV

Answer

Why

Correct — C.
Rule: three consecutive letters; each cluster starts on the last letter of the one before.

MNO ends in O → OPQ starts with O.
OPQ ends in Q → QRS starts with Q.
QRS ends in S → the next cluster starts with S.

Three letters from S: STU → option (c).

Why the others are wrong

(a)
RST — RST starts one step early, on R. The starts climb M, O, Q in twos, so the next is S, the letter QRS ends on.
(b)
RSP — RSP starts on R instead of S, and its letters are not consecutive: R, S, then back to P. Each given cluster is three letters in a row.
(d)
TUV — TUV starts on T, a step of 3. The starts climb M, O, Q by 2, so the next start is S.

Concept

Two numbers describe a consecutive-cluster series: the length of each cluster and the step between their first letters. Here the length is 3 and the step is 2: M(13), O(15), Q(17), S(19).

Because the step is one less than the length, each cluster shares one letter with the next: MNO and OPQ share O, OPQ and QRS share Q. With a step of 3, as in RST, UVW, XYZ, no letter would be shared.

RST and TUV sit one step either side of the answer, so the step has to be measured, not guessed from the look of the series.

Key facts

M, O, Q, S are positions 13, 15, 17, 19: the starts climb by 2.
With three-letter clusters and a step of 2, each cluster begins on the previous cluster's last letter.

Study next

Consecutive-letter series with a step of 3, which share no letterClusters whose letters are spaced out, such as AEI, EIM, IMQBackward consecutive-letter series

Common traps

Carrying over the step of 3 from RST, UVW, XYZ (Reasoning Q.4) and choosing TUV
Shifting QRS forward by one letter and choosing RST

14 Sep 2025, 09:00, Reasoning Q.4 also keys STU, but after JKL, MNO, PQR: a step of 3, so no letter is shared between clusters.

12 Sep 2025, 16:00, Reasoning Q.1 overlaps its clusters by two letters instead: AEI, EIM, IMQ, MQU, keyed QUY.

Related PYQs

No directly related past PYQ was found.

Topic: Semantic Series — all 87 SSC CGL questions on it, every solved shift.