Answer:
D
Step-by-step explanation:
red blood cell = 0.000009 = 9 × [tex]10^{-5}[/tex]
cold virus = 0.0000003 = 3 × [tex]10^{-7}[/tex]
Divide diameter of red blood cell by diameter of cold virus
[tex]\frac{9(10^-5)}{3(10^-7 )}[/tex]
= 3 × [tex]10^{-5-(-7)}[/tex]
= 3 [tex]10^{-5+7}[/tex]
= 3 × 10² → D
