The reason is ()?

The southbound device sends AT commands to SoftRadio through the serial port. As a result, SoftRadio does not display any information.

The reason is ()? (multiple choice)
A . SoftRadio received an unrecognized AT command
B . There is a problem with the connection between the southbound device and P’, SotRadio does not receive data
C . The sent AT command does not end with irin
D . All of the above are possible

Answer: B,C