Answer:
Technician b is correct
Explanation:
Before adjusting drive-belt tension, it is very important to check the vehicle workshop manual for specified belt tension, so that you can match your reading against the specification in the vehicle's service manual. If the tension reading you have matches the suggested reading in the vehicle's service manual and the belt is not damaged then you do not need to proceed any further. But if the reading does not match, then you can adjust the belt tension.
Therefore, technician b is correct.
Answer and Explanation:
The DC motor has coils inside it which produces magnetic field inside the coil and due to thus magnetic field an emf is induced ,this induced emf is known as back emf. The back emf always acts against the applied voltage. It is represented by 
The back emf of the DC motor is given by
Here N is speed of the motor ,P signifies the number of poles ,Z signifies the the total number of conductor and A is number of parallel paths
As from the relation we can see that back emf and speed ar dependent on each other it means back emf limits the speed of DC motor
Carbonation is more of a healer to the engine