Final answer:
A self-contained breathing apparatus (SCBA) combined with a hooded chemical resistant clothing splash suit would provide level 4 protection in BSL-4 laboratories.
Step-by-step explanation:
A self-contained breathing apparatus (SCBA) combined with a hooded chemical resistant clothing splash suit would provide level 4 protection. This level of protection is commonly used in BSL-4 laboratories where the most dangerous pathogens, such as Ebola virus and Marburg virus, are handled. The suit has its own air supply and maintains positive air pressure to prevent contamination from leaking into the suit.