We walked so quietly that the nurse at the desk didn't even lift her eyes from the book. Mum pointed to a big chair by the door and I knew she wanted me to have a seat. While I watched, mouth open in surprise, mum took off her hat and coat and gave them to me to hold. She walked quietly to tile small room by the lift and took out a wet mop (拖把). She pushed the mop past the desk and as the nurse looked up, mum nodded and said, "Very dirty floors."
"Yes. I'm glad they've finally decided to clean them," the nurse said. She looked at mum strangely and said, "But aren't you working late ？"
Mum just pushed harder, each swipe (拖) of the mop taking her farther and farther down the hall. I watched until I couldn't see her and the nurse had turned back to write in the big book.
After a long time mum came back. Her eyes were shining. She rapidly put the mop back and took my hand. As we turned to go out of the door, mum nodded politely to the nurse and said, "Thank you."
Outside, mum told me: "Dagmar is fine. No fever."
"You saw her, mum？"
"Of course. I told her about the hospital rules, and she will not expect us until tomorrow. Dad will stop worrying as well. It's a fine hospital. But such floors! A mop is no good. You need a brush."
When she took a mop from the small room what mum really wanted to do was ______.

A. to clean the floor
B. to please the nurse
C. to see a patient
D. to surprise the story-teller