Correct Answer: Defeat

Solution : The first option is the correct answer.

Vanquish means to defeat thoroughly or decisively. Defeat is a synonym, indicating overcoming an opponent or prevailing in a contest.

The meanings of other options are as follows:

• Acquit means to declare someone not guilty, especially in a legal context.
• Surrender means to yield or give up.
• Flee means to run away from a situation or danger.

Therefore, the correct answer is defeat.