Which of the following is NOT one of the four primary types of injury caused by exposure to liquid ammonia?

The correct choice identifies the type of injury that does not fall under the primary categories associated with liquid ammonia exposure. Liquid ammonia primarily poses risks through its chemical properties and physiological effects on human tissues.

Thermal burns and dehydration burns occur due to the extreme cold of the liquid ammonia, which can freeze tissues upon contact, leading to frostbite-like injuries. Moreover, respiratory burns result from inhalation of ammonia gas, which can severely irritate and damage the respiratory tract.

In contrast, electrical burns are not related to ammonia exposure, as they result from electrical currents traversing through the body, causing injury through heat generated by that electricity. Since ammonia does not deliver electric current, it does not cause electrical burns, making this answer the correct choice to the question posed.