Answer: Only technician A.
Explanation:
A 12 volt battery has 6 cells, where each cell produces around 2 volts.
Now, a battery cell has two sets of plates (or two main plates), one set of negative charged plates and other of positive charged plates, separated by an insulating material. Those plates are related to the amount of energy that can be stored by the battery, not with the voltage it has.
So the only one correct is technician A.