RAS question
Find the next letter in the series: A, E, I, O, ?
Correct answer: (D) U.
The next letter in the series A, E, I, O is U, because the series lists the English vowel letters in their usual order.
Explanation
The pattern is not based on alphabetic gaps or consonants; it is the standard sequence of English vowel letters. Merriam-Webster defines a vowel letter as a letter or symbol representing a vowel and notes that, in English, the term is usually used for a, e, i, o, u, with y sometimes included. The given series already contains A, E, I and O in that order, so the only usual English vowel left to complete the sequence is U. That makes option D the required continuation of the series.
Why the other options are wrong
- (A) S is a consonant, so it does not continue a series formed by the usual English vowel letters A, E, I, O and U.
- (B) T is a consonant and has no place in the ordered vowel sequence shown by A, E, I and O.
- (C) P is a consonant, whereas the pattern requires the next usual English vowel after O.
Concept
This tests letter-series recognition in reasoning, where the task is to identify the governing classification before choosing the next symbol. Such questions recur because they check whether a candidate can separate a simple category pattern from ordinary alphabet order.