The correct answer is B) ullage. Ullage refers to the distance between the surface of the liquid cargo and the top of the cargo tank. This is an important measurement for determining the volume of cargo remaining in the tank. Regulations and industry standards require the ullage to be measured and recorded as part of cargo operations. The other options are incorrect: - Innage refers to the depth of the liquid in the tank, not the distance to the tank top. - Thievage and tankage are not standard terms used to describe this measurement.