Which of the following terms will replace the question mark (?) in the given series? JKT, LJR, NIP, ?

Correct — C. Split the terms into three columns and read each as its own series.

First letters: J(10), L(12), N(14) — +2 each time → P(16)
Second letters: K(11), J(10), I(9) — −1 each time → H(8)
Third letters: T(20), R(18), P(16) — −2 each time → N(14)

P, H, N — option (c).

Why the others are wrong

• (a)
  PGO — The G drops two from I, but the second column falls by one at each step, so it gives H. The O in third place makes the opposite slip, moving one instead of two.
• (b)
  OGP — O is a single letter past N. The first column climbs by two — J, L, N — so the term has to open with P.
• (d)
  PHM — The first two letters are right; the M is three places back from P. The third column falls by two — T, R, P — so N is what follows.

A three-letter series is three separate series stacked on top of each other. Split the terms into columns before looking for anything cleverer.

Convert to alphabet positions and each column becomes a short number series. Here they are 10, 12, 14 climbing by two; 11, 10, 9 falling by one; and 20, 18, 16 falling by two.

Columns that move in different directions are the whole point of the item. A candidate reading the terms as words rather than as columns has nothing to work with.

Key facts

• First letters J, L, N advance by two, so the next is P.
• Second letters K, J, I fall by one, so the next is H.
• Third letters T, R, P fall by two, so the next is N.

Common traps

• Applying one column's step to all three letters.
• Reading the second column as a fall of two because the third column falls by two, which points at PGO.
• Counting the gap between two letters inclusively, so a step of two comes out as three.

No directly related past PYQ was found.