Which two substances found in animal facilities can cause severe frostbite?

The correct choice highlights liquid nitrogen and dry ice as substances that can cause severe frostbite.

Liquid nitrogen, at its boiling point of -196 degrees Celsius, is extremely cold and can cause immediate frostbite upon contact with skin or soft tissues. The rapid freezing of cells can lead to tissue damage similar to that caused by thermal burns.

Dry ice, which is solid carbon dioxide, sublimes at -78.5 degrees Celsius. Like liquid nitrogen, it can also cause frostbite through direct contact, resulting in frostbite due to its extreme cold temperature, which can freeze skin and underlying tissues.

Both substances are commonly found in laboratory animal facilities for refrigeration, cryopreservation, and other applications, necessitating proper handling and awareness of their potential hazards.

The context of the other choices involves substances that, while potentially hazardous in different ways, do not share the same immediate risk of causing frostbite as liquid nitrogen and dry ice. For example, substances like liquid helium and anhydrous ammonia have their own risks in terms of pressure or chemical burns but are not as commonly encountered in situations that would lead to frostbite in the way that liquid nitrogen and dry ice would.