A、The machine is broken. B、You can touch the machine anytime. C、The woman didn’t follow the advice. D、The working machine is dan

M: The rain stopped.last night. So it’s a fine day for a walk.
W: You are right. The air is nice and clean.
Q: What are they talking about?

M: Don’t touch the machine when it is working.
W: No, I won’t. Thanks for reminding me of it.
Q: What does the man mean?