Answer:
Both Technician A and B
Explanation:
The drop center or deep well allow for easy installation of tyre on the wheel when the tyre have same inner diameter as the wheel's outer diameter, one side of the tire must be placed into this depression on the wheel so that the tire can slide over just enough to let the other side of the tire slip over the rim edge. It also function to prevent the tyre from coming off the tyre in case of blown off or low tyre pressure.