Final answer:
The blood system is responsible for spreading a pathogen throughout the body.
Step-by-step explanation:
The body system responsible for spreading a pathogen throughout the body is the blood system. Pathogens, such as bacteria or viruses, can enter the bloodstream through various routes, such as open wounds or inhalation. Once in the bloodstream, these pathogens can be transported to different organs and tissues in the body, leading to infections.
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