Prior to getting underway in fresh or brackish water, the Master or person in charge of a MODU must __________.

Correct Answer: Option B — log the density of the water

46 CFR 109.203 mandates that when a MODU enters fresh or brackish water, the density of the water must be logged. This is essential for calculating the correct load line and ensuring the unit maintains adequate freeboard and stability in waters of varying buoyancy.