Answer:
I believe the answer is A
Explanation:
Answer:
Pandemics occur for two reasons. The first is a change in the infectious agent and the second is in human patterns. Both involve exposing people to agents they don’t have resistance to. Diseases like SARS, avian flu, and the famous Spanish flu all involved a mutation in the virus that resulted in a new disease that no one had resistance too. Examples of the second are when new groups of humans make contact, like small pox amongst native Americans, and possibly the black death.
Explanation:
Blood moves very slowly through capillaries. As the blood moves through a capillary, nutrients, oxygen, and food leave the blood and enter the body cells. ... Capillaries are exchange vessels. Gases (oxygen and carbon dioxide), nutrients, and wastes pass in both directions across capillary walls.
