a)
Vowels are letters A, E, I, O, U. Consonants are all other letters.
b)
Vowels are letters B, C, D, F, G. Consonants are letters A, E, I, O, U.
c)
Vowels are letters A, B, C, D, E. Consonants are letters F, G, H, I, J.
d)
Vowels are letters X, Y, Z. Consonants are letters A, E, I, O, U.
Correct answer is option 'A'. Can you explain this answer?