In the question below, a part is given in bold, which may not be in correct form. Choose the best replacement of it from the given options. If the sentence is correct as it is, choose “No replacement is needed” as the answer.

The researchers noted that chronic air pollution exposure can be altered the pulmonary immune system, may increase systemic inflammation.

Correct option is C

The correct answer is:
(c) exposure can alter the pulmonary immune system.
Explanation:
1. The original sentence has a tense error. The phrase "can be altered" is incorrect because it mixes the modal verb "can" (which requires a base verb) with "be altered," which suggests passive voice.
2. The correct construction should use the base form of the verb "alter" after "can." Therefore, "can alter" is the correct form.
3. The corrected sentence reads: The researchers noted that chronic air pollution exposure can alter the pulmonary immune system and may increase systemic inflammation.
Analysis of Options:
· (a) exposure could altered: This is incorrect because "could" (a modal verb) must also be followed by the base form "alter," not "altered."
· (b) exposure has altered: This changes the meaning to indicate a completed action in the present perfect tense, which is not consistent with the original intent of possibility.
· (c) exposure can alter: This is grammatically correct and aligns with the intended meaning.
· (d) exposure can altered: This is incorrect for the same reason as (a); "altered" cannot follow "can."
· (e) No replacement is needed: Incorrect, as the original phrase is not correct.
Thus, the best choice is (c).