He did me a good turn by recommending me for the post of Vice-Principal. A. became suddenly good B. improved my prospects C. did an act of kindness D. returned my kindness

became suddenly good
improved my prospects
did an act of kindness
returned my kindness

The correct answer is C.

A good turn is an act of kindness or generosity. In this case, the person recommended the speaker for the post of Vice-Principal, which is an act of kindness that could improve the speaker’s prospects.

Option A is incorrect because it does not describe an act of kindness. Option B is incorrect because it does not describe an act of kindness that could improve the speaker’s prospects. Option D is incorrect because it does not describe an act of kindness that the person did for the speaker.