The ball is in your court
We use this to indicate that someone else has to make a decision.
I have given you all the details of my car. You have all of the information that you need now. The ball is in your court if you want to make me an offer and buy it.
Remember that you won’t do yourself any favours if you simply throw these idioms into conversation during your IELTS interview. You must practice using them appropriately before the exam.