Select the appropriate idiom to fill in the blank.
The police have not yet been able to solve the case; it seems to be _________.
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. a hard nut to crack.
- This idiom is used to describe a problem or situation that is very difficult to solve or deal with.
- In the context of the sentence, it indicates that the police are finding the case challenging and have not been successful in solving it yet.