Loss of or weak residual magnetism in an alternator or generator can be corrected for by ______.
A.
running the rotor in the opposite direction for 5 minutes
B.
allowing the generator to run at 10% of normal speed for 5 minutes
C.
running the generator at normal speed with the field rheostat fully counterclockwise
D.
using a storage battery or battery charger to 'flash' the field