Select the most appropriate meaning of the given idiom.

A mare’s nest

Complicated situation

The most appropriate meaning of the given idiom "A mare’s nest" is (3) A complicated situation.

The other options do not fit the meaning of the idiom.

• A deep crisis is a very serious situation.
• Simple and interesting work is not a mare's nest.
• An area of law is not a mare's nest.

The idiom "a mare's nest" is used to describe a situation that is confusing or complicated. It is often used to describe a situation that is not what it seems to be.