Which of the listed conditions could cause a recently overhauled DC motor to have excessively hot windings and sparking at the brushes?

Correct Answer: Option C — Reversed interpole polarity

Reversed interpole polarity destroys the necessary flux opposition during commutation, inducing severe localized coil currents and heavy brush sparking. Per IEEE 45 and 46 CFR Subchapter J, this improper magnetic alignment rapidly overheates armature windings due to severe electrical and mechanical asymmetry during motor operation.