Select the most appropriate meaning of the given idiom.

Be hard up

The correct answer is Have very little money.

Explanation:

The idiom "be hard up" is an informal English expression used to describe a situation where someone has very little money or is in short supply of something essential.
For example: "He was so hard up that he couldn't afford to buy groceries."

Let's evaluate the given options:
1. Unable to calculate: This is incorrect as the idiom does not relate to math or calculation skills.
2. Have very little money: This is the correct meaning of the idiom.
3. Have difficulty in climbing stairs: This is a literal interpretation of the words "hard" and "up", which is incorrect.
4. Find it very difficult to wake up early: This is also incorrect and unrelated to the idiom's actual meaning.