Which of the following statements is true concerning the cleaning of electrical contacts?

Correct Answer: Option D — Delicate parts should be cleaned with a brush and an approved safety solvent.

Maintenance of electrical contacts requires precision to ensure conductivity and prevent arcing. Using approved safety solvents and a soft brush removes contaminants without damaging the contact material. Harsh abrasives or metallic tools are prohibited as they can score surfaces, leading to increased resistance and localized heating during high-current operation.