What is the LNG cargo term "rollover" used to describe?

Correct Answer: Option A — 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 describes the rapid mixing of stratified LNG layers of different densities and temperatures. When the layers equalize, a sudden release of stored thermal energy causes massive vaporization, rapidly overpressurizing the cargo tank and risking safety valve lifting.