Answer:
Step-by-step explanation:
In the passage from "The Hot Zone" by Richard Preston, Level 4 refers to an area that is highly hazardous and requires specialized protective gear for safety. Nancy, the character in the passage, compares passing through the gray-zone door into Level 4 to going on a spacewalk, except that instead of going into outer space, you are going into inner space, which is full of the pressure of life trying to get inside your suit. This suggests that Level 4 is an area with potentially deadly biological hazards, such as viruses or other infectious agents.
A "hot agent" is a term used to describe a highly infectious and deadly biological agent. In the context of the passage, a hot agent is specifically an unknown and amplified agent that poses a high level of danger. The passage suggests that performing a necropsy (an autopsy performed on an animal) on an animal that had died from exposure to such an agent was high-hazard work, emphasizing the seriousness of the situation.