Select the most appropriate meaning of the given idiom.

A hair in the butter

A challenging situation

The most appropriate meaning of the idiom "a hair in the butter" is (4) A challenging situation.

This idiom means that something is difficult or problematic. It is often used to describe a situation that is not easy to deal with or that requires a lot of effort to overcome.

For example, you might say that a test is a hair in the butter if it is very difficult.

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

• Easy to handle means that something is not difficult or problematic.
• A slippery road means a road that is covered in ice or snow and is therefore difficult to walk or drive on.
• Sinking in debt means that someone is accumulating debt and is having trouble paying it off.