The correct answer is: tangible.
Tangible proof is proof that can be touched or physically experienced. It is often used in legal cases to prove guilt or innocence. In the given example, the police need tangible proof of the man’s guilt before they can arrest him. This could include evidence such as fingerprints, DNA, or eyewitness testimony.
The other options are not as accurate as tangible. Convincing proof is proof that is likely to make someone believe something. Strong proof is proof that is very convincing. Emphatic proof is proof that is stated in a very forceful way. Clear proof is proof that is easy to understand.
In the given example, the police need proof that is more than just convincing, strong, emphatic, or clear. They need proof that is tangible, meaning that it can be physically experienced. This is because tangible proof is the most reliable type of proof. It is less likely to be misinterpreted or fabricated than other types of proof.