Final answer:
The type of atmosphere-supplying respirator that does not require the user to carry the air source is the Supplied-air respirator (SARs), which delivers clean air to the user via a hose from a remote source.
Step-by-step explanation:
The atmosphere-supplying respirators where the user does not carry the breathing air source are B. Supplied-air respirators (SARs). This type of respiratory protection includes systems where the clean air source is located away from the user, such as a compressor or high-pressure tank, and delivered to the user via a hose. SARs are commonly used in environments where hazardous substances can be present, and they provide a constant flow of air to the user, as opposed to Air-Purifying Respirators (APRs) and Powered Air-Purifying Respirators (PAPRs), which filter contaminants from the ambient air.
SARs are essential in situations such as firefighting, where firefighters wear breathing apparatus that benefits from aerospace technology transferred to civil-use applications, allowing communication and protection in smoke-filled environments. Moreover, such protective gear is crucial in specialized laboratories, like BSL-4 labs, where scientists deal with dangerous pathogens and must avoid exposure.