What is the meaning of the idiom " Pandora's box"?

The idiom "Pandora's box" means to cause many troubles and problems. It is a reference to a story in Greek mythology about a woman named Pandora who was given a box by the gods. She was told not to open the box, but she could not resist her curiosity and opened it anyway. When she did, all the evils of the world were released into the world. Only hope remained in the box.

So, the answer is (2) to cause many troubles and problems.

The other options are incorrect.

• (1) full of arguments is not the meaning of the idiom "Pandora's box".
• (3) free of evil is the opposite of the meaning of the idiom "Pandora's box".
• (4) to know a secret is not the meaning of the idiom "Pandora's box".