When tanks have been washed with crude oil, and ballasted without being water rinsed, the ballast is referred to as _________.

Correct Answer: Option B — dirty ballast

Ballast water taken into tanks that have been crude oil washed but not subsequently rinsed with water is classified as 'dirty ballast.' This water contains significant oil residue and must be handled according to strict MARPOL discharge requirements, typically requiring processing through an oily water separator or discharge to shore.