Explanation:

The correct answer is option 'C', "accusations we can". Let's break down the sentence to understand why this is the correct answer.

Subject and verb:
- The subject of the sentence is "one", which is a pronoun used to refer to an unnamed or unspecified person.
- The verb of the sentence is "go", which is the main action of the sentence.

Doubting the truth:
- The phrase "If one doubts the truth" introduces a condition or situation where someone is doubting the truth.
- This part of the sentence sets the context for what follows.

Accusations:
- The noun "accusations" refers to the claims or allegations made by the man.
- It is important to note that the accusatory statements are being made by the man, and the sentence is discussing them.

Going to the police:
- The phrase "we can always go to the police" suggests a possible course of action when there is doubt about the truth of the accusations.
- The word "always" emphasizes the reliability and availability of the option to seek help from the police.

Putting it all together:
- The sentence states that if someone doubts the truth of the man's accusations, there is an option to go to the police.
- It implies that seeking help from the police can help clarify the situation and determine the truth of the accusations.

Other options:
- Option 'A', "If one doubts the truth", is the introductory part of the sentence that sets the context. It is correct grammatically, but it is incomplete without the rest of the sentence.
- Option 'B', "of the mans", is not a complete phrase or sentence. It is grammatically incorrect.
- Option 'D', "always go to the police.", is the concluding part of the sentence that suggests a course of action. It is correct grammatically, but it is incomplete without the context provided in the previous parts of the sentence.