A Crude Oil Wash (COW) system is considered as __________.

Correct Answer: Option D — a Butterworth system using crude oil instead of water as the cleaning medium

Crude Oil Washing (COW) is a specialized tank cleaning method mandated by MARPOL. Unlike traditional water-based Butterworth systems, COW utilizes the crude oil cargo itself as the cleaning medium, sprayed through fixed machines to dissolve and remove waxy residues from tank surfaces, thereby reducing pollution and increasing cargo recovery.