Network Diagnosis Is Being Discussed

Network diagnosis is being discussed. Technician A says that a test light can be used at the DLC to determine if the CAN bus has activity. Technician B says that a break-out box can be used to determine if there is activity on the CAN bus. Which technician is correct?

A) Technician A only
B) Technician B only
C) Both technicians A and B
D) Neither technician A nor B