Explanation:

- Pull someone up often means to criticize someone, especially to correct or address a mistake or behavior.

- Option 1: Agree with someone - This means to have the same opinion or to concur with someone.

- Option 2: Drag someone - This means to physically pull or move someone along, not typically relevant to the idiom.

- Option 3: Criticise someone - To point out someone's mistakes or reprimand them to prompt improvement.

- Option 4: Help someone - To assist or aid someone, does not convey criticism or reprimand.

Option 3: Criticise someone is indeed the correct interpretation of the idiom "pull someone up."