Technician a Says That Without the Pressure Differential Sensor (Delta

Technician A says that without the pressure differential sensor (delta P sensor) , the exhaust DPF would not regenerate, because the amount of soot loading would not be able to be properly calculated. Technician B says that the amount of soot loading is only estimated, and not accurately measured, using the delta P sensor. Who is correct?

A) Technician A"
B) Technician B"
C) Both A and B
D) Neither A nor B"