Which one works as an output and input device?

a) Scanner -    its an input device.

b) Modem  ---  Modem is both an input and output devices it modulate and demodulate the signal. it convert the digital signal to analog and analog signal to digital.              

Scanner is an Input device and modem is both input and output device.

both scanner and modem can be a i/o device

>>>>>>>>>>>>>>>>>>>>>>>>>  b) Modem  

here scanner works as an input and output device

Output and Input Device is a Modem

Scanner ia an input and output device option a

The a) Scanner works both as an output and input device.

Scanner is the input/ output device