Technician a Says That the Connecting Rod and Main Bearing

Technician A says that the connecting rod and main bearing caps should be marked before removing to ensure that they can be reinstalled in the exact same location when re-assembled. Technician B says that the tip of the valve stem should be filed before removing valves from the cylinder head to help prevent damage to the valve guide. Who is right?

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