Select the letter-cluster from among the given options that can replace the question mark (?) in the following series. BRF , EUH , HXJ , KAL , ?

Correct — D.
Rule: first and second letters +3, third letter +2.

First: B, E, H, K → K(11) + 3 = N(14).
Second: R, U, X, A → A(1) + 3 = D(4).
Third: F, H, J, L → L(12) + 2 = N(14).

That gives NDN → option (d).

Why the others are wrong

• (a)
  NMB — NMB has the right first letter, but M is twelve places after A. The second letters step +3, so after A comes D, and the third letter should be N, not B.
• (b)
  NKH — NKH gets N right and then breaks: K is ten places after A, and H is four places before L. The steps are +3 and +2, giving D and N.
• (c)
  NHG — NHG puts H second, seven places after A. The second letters step +3, R, U, X, A, so the next is D, and the third letter should be N, not G.

Every option begins with N, so the first position separates nothing. The second position is the instructive one, because it runs past Z: R(18), U(21), X(24), then 27, which restarts at A(1).

Once you see that X + 3 wrapped to A inside the question, A + 3 = D follows. The third letters are a plain +2 run to N, which confirms it.

Key facts

• After Z the count restarts at A, so X(24) + 3 = A(1).
• R, U, X, A, D is a +3 run with one wrap past Z.
• F, H, J, L, N is a +2 run.

Common traps

• Reading KAL as a break in the pattern instead of a wrap past Z
• Trying to decide on the first letter, which all four options share

No directly related past PYQ was found.