Select the most appropriate meaning of the given idiom.

Plain as day

Very obvious and easy to understand

The most appropriate meaning of the idiom "plain as day" is Very obvious and easy to understand.

The idiom "plain as day" means that something is very easy to see or understand. It is often used to describe something that is very obvious, but that someone may be trying to ignore or deny.

For example, you might say that the evidence against a suspect is "plain as day" if it is clear that they are guilty. Or, you might say that the instructions for assembling a piece of furniture are "plain as day" if they are easy to follow.