Which of the listed substances can be satisfactorily removed from diesel fuel by centrifuging?

Correct Answer: Option A — Sludge

Centrifuges utilize high-speed rotation to exert centrifugal force, separating substances based on specific gravity. Sludge, consisting of dense solids and water, is effectively removed from fuel. Gasoline, lube oil, and fuel oil are typically the carrier fluids or contaminants that cannot be separated from themselves via this process.