Which of these letters is not a consonant?

Explanation

The modern English alphabet is a Latin alphabet consisting of 26 letters - a b c d e f g h i j k l m n o p q r s t u v w x y z. The letters a, e, i, o, and u are considered vowel letters. A vowel is also an isolated sound - you can sing or shout it - you can't do that with other letters. The letter most frequently used in English is E. The least frequently used letter is Z.