Select the most appropriate idiom for the sentence given below.

The detective suspected Shyam because of his odd behaviour while investing in the scam.

To smell a rat

The most appropriate idiom for the sentence is to smell a rat. This idiom means to suspect that something is wrong or suspicious. It is used to describe someone who has a gut feeling that something is not right, even though there may be no concrete evidence to support their suspicions.

In the sentence, the detective suspects Shyam because of his odd behavior while investing in the scam. The detective may not have any concrete evidence to support his suspicions, but he can sense that something is not right.

The other idioms are not as appropriate for the sentence.

• To hang fire means to be delayed or postponed. This does not make sense in the sentence, as the detective is not delaying or postponing his suspicions.
• To bite the dust means to die. This is not what the detective is doing. He is not dying, he is simply suspicious of Shyam.
• A dog in the manger is someone who is unwilling to share something that they do not need. This does not make sense in the sentence, as the detective is not unwilling to share his suspicions.