Which of the following will prevent a flammable atmosphere from occurring in a cargo tank on a tank vessel?

Using inert gas is a method employed to prevent a flammable atmosphere from developing in a cargo tank on a tank vessel. When inert gas, such as nitrogen or carbon dioxide, is introduced into the cargo tank, it reduces the oxygen concentration to a level below what is needed to support combustion. This process effectively dilutes the flammable vapors that may be present, creating a safer environment and minimizing the risk of fire or explosion.

Inerting is particularly important during the loading and unloading processes and in transport, as it ensures that there is a challenge to any potential ignition sources. It also helps to protect stored cargo from oxidation. The other options listed do not effectively address the issue of flammable atmospheres in the same way. A combustion stabilizer is designed to enhance combustion rather than prevent it. An oxidizer provides the necessary oxygen for combustion, which would increase the likelihood of a fire. A vortex eliminator, while it can improve flow dynamics and reduce turbulence in some contexts, does not mitigate flammability in the atmosphere of a cargo tank. Thus, the introduction of inert gas remains the most effective strategy for maintaining safety in such environments.