Select the most appropriate meaning of the given Idiom:-

To Smell a rat 

Suspect something foul

The most appropriate meaning of the idiom "to smell a rat" is to suspect something foul. The idiom comes from the idea that rats are associated with danger or trickery. In a figurative sense, to smell a rat means to suspect that something is wrong or suspicious.

The other options are not as accurate descriptions of the meaning of the idiom. Having foul smell in home is not the same as smelling a rat. Extremely difficult task is not typically associated with the idiom "smell a rat." A clandestine plan is not typically associated with the idiom "smell a rat."