The SPEED TRIM FAIL light illuminates after pressing the system

The SPEED TRIM FAIL light illuminates after pressing the system annunciator to recall and distinguishes when reset the Master Caution system. What does this mean?

A.The speed trim system fails.

B.The speed trim system single channel fails and the speed trim system can operate normal.

C.It‘s a normal indication. the speed trim system does not operate in the following flight.

正确答案是B