With reference to Liquefied Gas operations, what does the term "rollover" used to describe?

Correct Answer: Option C — when two or more stratified layers of different density LNG in the same tank suddenly mix together, causing a rapid increase in boil-off vapors

Rollover occurs in LNG tanks when stratified layers of different densities suddenly mix due to heat ingress. This rapid mixing releases a massive volume of vapor as the liquid reaches equilibrium, potentially exceeding the capacity of the boil-off gas handling system and causing dangerous pressure spikes within the tank.