Which letter cluster will replace the question mark (?) in the following series?
CD, FH, IL, LP, OT, ?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → RX
In a letter-cluster series the first and second letters each follow their own rule, so each position is checked separately using the place of the letter in the alphabet.
First letters C (3), F (6), I (9), L (12), O (15): 3 places ahead each time, so the next is \(15+3=18\), that is R
Second letters D (4), H (8), L (12), P (16), T (20): 4 places ahead each time, so the next is \(20+4=24\), that is X
So the missing cluster is RX.