Correct Answer: Doesn't hold water

Solution : The fourth option is correct.

• The given sentence implies that the evidence presented was not enough or consistent enough to prove the person's guilt .
• The idiom doesn't hold water is used to say that an argument or suggestion doesn't stand up to scrutiny or isn't valid or credible.
• This idiom fits perfectly within the context of the sentence, as the phrase could not confirm his guilt, implying that the evidence put forward was insufficient or unpersuasive.
• Thus, to say that the evidence doesn't hold water means it couldn't fulfill its purpose of conforming guilt, as water leaking from a container signifies an unreliable or inadequate container.

Therefore, the correct answer is: " Doesn't hold water ."