A、Remove it. B、Replace it. C、Press a button. D、Not mentioned. A根据对话中“it starts when you remove it!”可以判断此题答案为A

Rachel: What enormous twin beds! And look at those huge pillows on them! Let me try the beds. Oh, the mattress feels too soft for my liking!
Lin: Look at the toiletries in the bathroom — shampoo, bath-foam, even a shower hat!
Rachel: Look at that small device on the wall of the bathroom. What’s that?
Lin: Oh, it must be a hair drier. I wonder how it works. Oh, it starts when you remove it!
Rachel: You’d better put it back.
Lin: I guess so.
Rachel: Let’s go and see the room again. Look, there’s a balcony with some chairs on it. Wow! Look, what a wonderful view!
Lin: Yes, —look at that huge container ship! It must be heading for the harbor. And look at that beautiful cruise ship down there, alongside the quay!
Rachel: What’s that in the distance, just behind the container ship? Is it the mainland?
Lin: No, that’s an island. The mainland is on the other side of the island, to the north.
Rachel: To have a balcony connected to your room is great. I say, Lin, there’s a mini-bar under the TV. Shall we have a drink on the balcony and watch the sunset?
Lin: I don’t think we should touch the mini-bar—just look at the prices! Let’s freshen up, and then go down to the Rainbow Bar and use our vouchers!
Rachel: Good idea!
Lin: Let’s go!