What action should be taken if the tank is completely full?

Answer: B — Never load the tank completely full

When transporting liquid cargo, particularly in tanks, it's crucial to understand the principle of expansion and the phenomenon known as "slosh." If a tank is filled to capacity, there is no room for the liquid to expand, which can lead to pressure buildup. This pressure can be dangerous and may cause leaks or even ruptures in the tank. Moreover, a completely full tank does not allow for the natural movement of the liquid that might occur during transit, which can negatively affect vehicle handling and stability. Filling a tank completely removes the necessary space for liquids to slosh and move, which can cause an uneven load and increase the risk of rollover or loss of control during braking or turning maneuvers. Therefore, it is essential to leave appropriate headspace in the tank to ensure safe transportation and to accommodate any expansion of the liquid. This practice is a critical safety measure in the transportation of liquids.