He is ___ M.A:

The correct answer is "an". The choice between 'a' and 'an' depends on the sound of the word immediately following the article, not necessarily the letter. When 'M.A.' is pronounced, the 'M' starts with a vowel sound (em-ay).

• "a" is used before words that begin with a consonant sound.
• "the" is a definite article, used for specific nouns, not for general qualifications in this context.
• "no article" would be grammatically incorrect as 'M.A.' is a countable noun here.