Vowel is a speech sound produced without significant constriction or closure of the vocal tract.

• A. Consonant
• B. Vowel
• C. Fricative
• D. Stop

Answer: (B)

The main idea is how the vocal tract is shaped when producing a sound. A vowel is produced with an open vocal tract—there isn’t significant constriction or closure, so air flows freely and the sound is shaped mainly by the position of the tongue and lips. This open configuration also makes vowels the core of syllables and typically voice requires little to no obstruction.

Consonants, fricatives, and stops all involve some degree of constriction: consonants have a noticeable obstruction, fricatives produce noise by a narrow gap causing turbulence, and stops involve a complete closure followed by a release. That’s why the description fits vowels best.