The number of pure vowels is:

Correct option is D

English has 12 pure vowels (monophthongs), characterized by a single, unchanging tongue and lip position during articulation. These include /iː/, /ɪ/, /ʊ/, /uː/, /e/, /ə/, /ɜː/, /æ/, /ɑː/, /ɒ/, /ɔː/, and /ʌ/.
Information Booster
1. Pure vowels have a stable sound quality throughout articulation.
2. They are categorized by tongue height (high, mid, low) and position (front, central, back).
3. Essential for clear pronunciation and distinguishing words.
4. Differ from diphthongs, which glide between two vowel sounds.
5. Used in phonemic transcription to standardize English pronunciation.