When reentering an engine room that has been flooded with CO2, the investigating team should initially __________.

Correct Answer: Option D — enter from the highest level with breathing apparatus

CO2 is heavier than air and will settle at the lowest points of a compartment. Entering from the highest level, while wearing a self-contained breathing apparatus (SCBA), ensures the team remains above the highest concentration of the gas, providing a safer vantage point for assessment and ventilation operations.