Based on the English alphabetical order, three of the following four letter-cluster pairs are alike in a certain way and thus for…

Question

Based on the English alphabetical order, three of the following four letter-cluster pairs are alike in a certain way and thus form a group. Which is the one that does not belong to that group? (Note: The odd one out is not based on the number of consonants/vowels or their position in the letter cluster.)

1. A. RO-VT
2. B. LI-PN
3. C. PM-TR
4. D. NK-RO (Correct answer)

Correct Answer

Option D — NK-RO

Detailed Solution & Explanation

The correct answer is NK-RO.

Key Points

• Test the shift applied to each letter of the pair:
  • RO-VT: R+4=V, O+5=T
  • LI-PN: L+4=P, I+5=N
  • PM-TR: P+4=T, M+5=R
  • NK-RO: N+4=R, K+4=O
• Three pairs follow the pattern (+4, +5). NK-RO applies (+4, +4), so it is the odd one out.

Additional Information

• The first letter shifts by 4 in all four pairs, so checking only the first letter reveals nothing — the discriminator is entirely in the second letter.
• The question's note that the answer is not based on the number of consonants is a deliberate steer away from a false trail; take such notes seriously, as they eliminate an entire line of enquiry.
• Write the shifts as a numeric signature for each pair — (4,5), (4,5), (4,5), (4,4) — and the outlier is visible at a glance without holding letters in mind.
• Where every pair shares the first shift, always test the remaining positions; question setters routinely make the first element uniform precisely to absorb a careless glance.