Before a tank is to be crude oil washed, the oxygen content in the tank must be measured at a position __________.

Correct Answer: Option B — one meter from the deck

MARPOL Annex I and industry standards for Crude Oil Washing (COW) require oxygen measurements to be taken one meter below the deck through the deck opening. This specific depth ensures the sample is representative of the tank atmosphere while avoiding the immediate boundary layer near the deck plating.