【单选题】A Phone That Knows You're busy It's a modern problem: You're too busy to be disturbed by incessant (连续不断的)phone calls so you turn your cellphone off. but if you don't remember to turn it back on when ...
A.
they must tolerate phone disturbances or miss important calls.
B.
they must turn off their phones to keep their homes quiet.
C.
they have to switch from a desktop phone to a cellphone