Final answer:
The SCBA (Self-Contained Breathing Apparatus) is the mask that provides comprehensive protection from chemical and biological agents, especially in highly hazardous environments such as BSL-4 laboratories.
Step-by-step explanation:
The mask that protects you from chemical and biological agents is the Self-Contained Breathing Apparatus (SCBA). The SCBA provides the most comprehensive protection in environments with dangerous chemicals and biological hazards, ensuring the wearer breathes in clean air from an independent source. This is crucial when working with highly infectious or toxic agents, such as those found in BSL-4 laboratories, which require the highest level of containment and personal protective equipment. The SCBA consists of a protective suit, a full-face mask, and an air tank, and maintains a higher internal air pressure to prevent the ingress of contaminated air. Other options, like the N95 respirator, surgical mask, and dust mask, do not provide adequate protection against highly dangerous chemicals and pathogens.