Which of the following terms will replace the question mark (?) in the given series? HPL, KLQ, NHV, QDA, TZF, ?

Correct — A. Rule: first letter +3, second letter −4, third letter +5, each position running its own chain.

First letters: H, K, N, Q, T, so T + 3 = W
Second letters: P, L, H, D, Z, so Z − 4 = V
Third letters: L, Q, V, A, F, so F + 5 = K

Both wraps are already tested inside the series: the second chain runs past A (D − 4 lands on Z) and the third runs past Z (V + 5 lands on A).

The missing term is WVK — option (a).

Why the others are wrong

• (b)
  XVK — The second and third letters are right, but X is +4 from T where the first chain moves +3. The next first letter is W.
• (c)
  WDK — D is the second letter of the fourth term, QDA, not the next one. Continuing the −4 chain from Z gives V.
• (d)
  XWK — Both of the first two letters overshoot: X is +4 from T and W is −3 from Z, where the chains run +3 and −4.

A three-letter series is three independent single-letter series stacked together. Solve them one column at a time and never read the terms as words.

Write the alphabet positions down each column. Here the columns move +3, −4 and +5, and each keeps its own step for the whole series.

Wrapping is what catches people. Treat the alphabet as a circle: below A you continue at Z, above Z you continue at A. That is how D − 4 reaches Z and V + 5 reaches A.

Key facts

• The first letters are H, K, N, Q, T, W — a +3 chain.
• The second letters are P, L, H, D, Z, V — a −4 chain that wraps past A.
• The third letters are L, Q, V, A, F, K — a +5 chain that wraps past Z.
• Positions used: H=8, K=11, N=14, Q=17, T=20, W=23.

Common traps

• Stopping the −4 chain at D because the alphabet appears to run out, instead of wrapping round to Z
• Reading the terms as words and hunting for a meaning in them
• Applying one column's step to all three letters of a term

No directly related past PYQ was found.