Select the most appropriate meaning of the idiomatic expression given.

Caught red-handed

Caught in the act of doing something illegal

The most appropriate meaning of the idiomatic expression "Caught red-handed" is: Caught in the act of doing something illegal.

Explanation:
"Caught red-handed" is an idiom used to describe someone who is caught in the midst of committing a wrongdoing or engaging in illegal activities. It implies being caught in the act of committing the offense, often with clear evidence of guilt. Therefore, "Caught in the act of doing something illegal" accurately reflects the meaning of this expression.