Correct Answer: MNOP

Solution : Given:

A, CD, GHI, ?, UVWXY

Each letter cluster is consecutive alphabetical series and the number of letters in consecutive letter clusters is one more than the previous one.

Also, the difference between the letter clusters is equal to the number of letters in the next letter cluster.

A, CD → CD has two letters, therefore, difference between them will be 2.

A + 2 = C. → CD.

CD, GHI → GHI has three letters, therefore, difference between them will be 3.

D + 3 = G.

GHI, ? → This missing letter will have 4 letters, therefore difference is also equal to 4.

I + 4 = 9 + 4 = 13 → M.

4 consecutive alphabets from M → MNOP

MNOP, UVWXY → UVWXY has five letters, therefore, difference between them will be 5.

P + 5 = U.

Therefore, MNOP is the missing term and the series is as follows –

A, CD, GHI, MNOP, UVWXY

Hence, fourth option is correct.