Choose the part of the sentence that contains an error:
You should avail of every opportunity.

Correct option is C

Option (c) contains an error.
Explanation: The verb avail in the sense of “make use of / take advantage of” is normally used reflexively in standard English: avail oneself of + noun. Therefore, the sentence should be “You should avail yourself of every opportunity.” Here, the reflexive pronoun yourself must agree with the subject You. The other parts are correct.
Grammatical rule used:
· With the meaning “to use/take advantage of,” the pattern is avail + reflexive pronoun + of + object.
· Structure: Subject + avail + oneself (myself/yourself/himself/…/themselves) + of + noun.
Example:
· Correct: They availed themselves of the early-bird discount.
· Correct: She availed herself of every learning resource.