Answer: Both technicians are correct. 
It is true when technician A says that the octane rating of a gasoline is used to measure the antiknock properties of a gasoline. Octane rating measure the resistance of gasoline to engine knocking in spark-ignition internal combustion of engines. 
On other hand, technician B is also correct because a normal combustion occurs smoothly, controlled burning of air and fuel mixture then progresses across the combustion chamber from the point of ignition.