The doctor told his patient about all the things that could impair his health.

Analyze the question: You are asked for the word closest in meaning to impair in the sentence: "The doctor told his patient about all the things that could impair his health."

Explain the concept: To impair something means to weaken it or make it worse, so that it no longer works as well as it should. It is often used with health, vision, hearing, judgment or performance. The idea is harm or reduced quality, not complete destruction.

Solution, going through the options:

• A. attack: This means to act aggressively against something. Things that impair health may attack it, but "attack" does not mean "impair."
• B. terminate: This means to end completely. Impairing is only partial harm, not ending something totally, so this is too strong.
• C. damage: This means to harm or spoil something. It fits perfectly: things that could damage his health.
• D. reduce: This means to make smaller in amount or size. It is close, but it is about quantity, while impair is about quality or function. Health is damaged rather than "reduced" in this sense.

Answer: The best match is C. damage.

Tip: Link impair with words like "weaken, harm, spoil." Remember the phrases visual impairment and hearing impairment, which describe damaged function. In "nearest in meaning" questions, substitute each option into the sentence and pick the one that keeps the original sense.