Case 1: When the 2nd letter is m:
The 1st letter can be any of the 5 vowels.
The 3rd letter will be any of the 4 remaining vowels
Number of possible 3 letter combinations = 5 × 4 = 20
Case 2: When the 2nd letter is n:
The 1st letter can be any of the 5 vowels.
The 3rd letter will be either e or u.
Number of possible 3 letter combinations = 5 × 2 = 10
Case 3: When the 2nd letter is p:
The 1st letter can be any of the 5 vowels.
The 3rd letter will be the same as the 1st letter.
Number of possible 3 letter combinations = 5 × 1 = 5
Total number of possible 3 letter combinations
=20 + 10 + 5 = 35
Hence,Option (D)35 is the correct choice.