The Gate Hotel

A. There will be noise when the glass plate slides towards the door, but the door doesn't open, indicating that the voice control device is not used.

B, the glass plate will also emit infrared rays, but the door is not opened, indicating that it is not the infrared rays emitted by the detection object to realize automatic opening and closing.

C. If the automatic door emits infrared rays, the infrared rays will be rarely reflected through the glass, but football and people will reflect more infrared rays, because infrared rays cannot penetrate football and people. Automatic doors can detect reflected infrared rays and realize automatic opening and closing.

D, the glass plate can also give the automatic door a pressure through the air, but when the glass plate slides towards the automatic door, the automatic door does not open, which means that the automatic switch is not realized by air pressure.

So choose C.