B. Sand.
Sand would definitely increase friction because of the roughness of it surface. When its surface comes with another rough surface it would tend to increase friction. All other options given tend to reduce friction one way or the other.
CO2 is carbon dioxide which is most famous for being in gas form so i would figure if it was exposed to freezing temperatures it would turn into a liquid then maybe a solid<span />
Explanation:
The lack of a control group
Answer:
answer is 0.001168 is correct
