Answer:
Virus
Explanation:
According to Dmitri Ivanovsky, Virus are the smallest pathogens. In fact, some of them actually infect bacteria too.
<u>-TheUnknownScientist</u><u> 72</u>
He could make sure he exercises regularly to keep the blood flow pumping to his heart, he can eat healthy so that he does not have a lot of fat build up in his arteries and he can also stay away from smoking to keep his body functioning properly.
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The root word which means "red" is a. erythr/o.
Just think about biology - you should know that red blood cells are called erythrocytes, where you can obviously see that root word.
Leuk/o refers to white color, and the other two options do not refer to colors at all.