Select the correct combination of letters that when sequentially filled in the blanks of the given series will make the series logically complete. B_FH_LNP_T_X

Correct — D. Read the letters already printed before touching the options.

Rule: each letter is two places after the one before it — B, D, F, H and so on, the even-numbered letters of the alphabet.

The visible stretches F, H and L, N, P already step by 2, which fixes the step for the whole line.

Fill the blanks in order: after B comes D, after H comes J, after P comes R, after T comes V.

That is D, J, R, V, and the completed series reads B D F H J L N P R T V X — option (d).

Why the others are wrong

• (a)
  CKSU — C, K, S and U sit at positions 3, 11, 19 and 21, so the line would open B, C, F — a one-place step followed by a three-place step.
• (b)
  DIQU — D is right but I, Q and U are odd-numbered; H to I is a single step where every other gap in the line is two.
• (c)
  CIQW — C, I, Q and W are all odd-numbered letters, while every letter already printed is even-numbered, so none of the four can fit.

A blank-filling letter series hands you most of the pattern. Number the alphabet A = 1 to Z = 26, write the positions of the letters that are printed, and the step announces itself.

Here the printed letters are B, F, H, L, N, P, T and X — positions 2, 6, 8, 12, 14, 16, 20 and 24, every one of them even. So any option carrying an odd-numbered letter is out before a single blank has been filled.

Key facts

• A = 1 through Z = 26 is the position table every letter-series item runs on.
• The printed letters B, F, H, L, N, P, T, X sit at positions 2, 6, 8, 12, 14, 16, 20, 24.
• Filled with D, J, R and V the series reads B D F H J L N P R T V X, a constant step of two.

Common traps

• Filling the first blank correctly and assuming the rest of the option follows
• Losing count of the step across the longer printed stretches
• Reading the four answer letters as consecutive letters of the alphabet

No directly related past PYQ was found.