In the given sentence, the word "retract" is used, and it means to withdraw or take back something that has been said or written. The most suitable synonym from the options provided is "withdraw" (Option C).

Here's a brief explanation of each option:

A. Alter: To change or make a modification, but it doesn't specifically imply taking back a statement.

B. Refine: To improve or make more precise, but it doesn't convey the idea of taking back a statement.

C. Withdraw: To take back or remove. In the context of the sentence, retracting a statement involves withdrawing it.

D. Deny: To refuse to admit or acknowledge; while denying a statement is related, it may not capture the sense of taking it back or withdrawing it.

Therefore, "withdraw" (Option C) is the word that is nearest in meaning to "retract" in the given sentence.