Select the most appropriate meaning of the given idiom.

Slack off

To ease pressure on something

The most appropriate meaning of the idiom "slack off" is (2) To ease pressure on something.

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

• To understand a hidden meaning is to figure out something that is not obvious.
• To make most effort is to try very hard.
• To be very rude is to be impolite or disrespectful.

The idiom "slack off" means to relax or not work as hard as you should. It is often used to describe someone who is not putting in their full effort at work or school.