Catch (someone) red-handed

Do you know the English expression “to catch (someone) red-handed“? Read the conversation below. Can you guess the meaning?

Gary: Who stole the money from the safe?

Liam: It was Trevor. I caught him red-handed. 

Gary: He must have been surprised to see you!

Liam: He was! He tried to pretend he was counting the money, but he couldn’t explain why it was in his pocket!

Does it mean:

a) to make someone’s hand’s red

b) to catch someone in the act of doing something

c) to help someone steal something

d) to catch someone with dirty hands

The answer is below! ↓

 

Answer: b) to catch someone in the act of doing something