Select the grammatically correct sentence.
The old man who was found dead on the track wore a red shirt with no sleeves.
All four sentences use the same words and differ only in their articles, so this is purely a test of article use. Two rules apply throughout.
Rule 1 — a or an is chosen by sound. An before a vowel sound, a before a consonant sound.
Rule 2 — the marks something already identified; a/an introduces something for the first time.
Option 1 is wrong: 'A old man' should be an old man, since old begins with a vowel sound.
Option 2 is wrong: 'an track' should be the track or a track, because track begins with the consonant sound t.
Option 4 is wrong: 'an red shirt' should be a red shirt, as red begins with the consonant sound r.
Option 3 gets every article right. 'The old man' is definite because the relative clause 'who was found dead' identifies exactly which man is meant. 'The track' is a particular track. And 'a red shirt' introduces the shirt for the first time, so the indefinite article is correct there.
The answer is option 3.
Method: when options differ only in small function words, compare them position by position rather than reading each sentence whole.
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