The person that is correct based on the 2 statements from Tech A and Tech B is; Tech B
A mass flow sensor is defined as a sensor that is used to measure the mass flow rate of air entering a fuel-injected internal combustionengine and then sends a voltage that represents the airflow to the electronic control circuit.
However, for Tech A is incorrect and so the correct answer is that Tech B is right because his statement corresponds with the definition of mass flow sensor.