What action should you take after each 25-gallon increment of fuel is pumped?

After each 25-gallon increment of fuel is pumped, it is crucial to take soundings. This process involves measuring the fuel level in the tank to ensure accurate record-keeping and to monitor the amount of fuel being added. Taking soundings helps maintain a clear understanding of how much fuel is actually in the tank post-refueling, which is essential for operational safety and efficiency. It allows the crew to detect any discrepancies that may occur during fueling, such as overfilling or leaks. This practice is a fundamental part of effective fuel management aboard the vessel.

While other actions, like inspecting for leaks or checking the oil level, are important for overall vessel maintenance and safety, the immediate action after refueling relates directly to confirming fuel levels and ensuring proper fuel management. This is why taking soundings is emphasized as the correct response in the context of this question.