Answer:
The correct sentence should be:
I wear ( an ) extra small.
Explanation:
whenever there's a word that starts with a vowel, we use 'an' before it. In our case, extra starts with 'e' which is a vowel, therefore we use 'an' before it. Similarly, if the word starts with a consonant (not a vowel), then we use 'a' before it.
hope that helps...
