Concept:The word "retract" means to take back something said or written, so we need the closest synonym from the options.
Explanation:"Retract" means to withdraw a statement, opinion, or promise.
Option A, "alter," means to change something, not to take it back.
Option B, "refine," means to improve or make something more precise.
Option C, "withdraw," means to take back or remove; this matches the meaning of "retract."
Option D, "deny," means to refuse to admit something, which is not exactly the same as taking it back.
Among all the options, "withdraw" is the closest in meaning.
Answer:C. withdraw