Prior to entering a compartment containing an atmosphere potentially dangerous to life or health and deficient in oxygen, you should don an approved breathing apparatus. Which of the listed devices would be suitable?

Correct Answer: Option A — An SCBA.

In oxygen-deficient or toxic atmospheres, only a Self-Contained Breathing Apparatus (SCBA) provides the necessary protection. Unlike canister masks or filter respirators, which rely on ambient air, an SCBA provides an independent supply of breathable air, which is mandatory for entry into enclosed spaces per OSHA and SOLAS requirements.