Select the most appropriate meaning of the given idiom:

know inside out

To know something thoroughly

The most appropriate meaning of the idiom "know inside out" is to know something thoroughly.

The other options are incorrect.

• "To know a little about something" is not the same as know inside out. Know a little about something means to have a basic understanding of something, while know inside out means to have a complete and in-depth understanding of something.
• "To know everything by rote memory" means to be able to recite something without understanding it, while know inside out means to have a complete and in-depth understanding of something.
• "To always know a lot about every topic" is not the same as know inside out. It is possible to know a lot about a lot of topics without knowing any of them thoroughly.

The idiom "know inside out" comes from the idea of knowing something so well that you know it from the inside out. In the same way, someone who knows something inside out is someone who knows it very well, including all the details and nuances. For example, you might say that a mechanic knows cars inside out if they can fix any problem with a car.