Answer:
C
Explanation:
C, your body needs more boold when you are running!
I am pretty sure it is B. diaphragm hope it help
Viruses need a host because a host is just like the owner of the virus "business". think of it as a company. the company has a boss- aka the person who made the company (this is the host) and the boss also tells the employees (bacteria etc) what to do and how to do it. without the host, the virus will die. :)