21. The scientists who signed the petition believed that
atomic weapons
A. would not help bring the war to a quick end.
B. should be used immediately to end the war!
C. might be used if there was no other option.
D. were too dangerous to use for any reason.

c- cold periods in earth's history during which glaciers covered much of the surface.

explanation:

the correct answer would be b. amelia, because the particals of gas move really fast (charged particals) and gas also has a lot of room (particals move independently) so the only answer that has both of those is amelia's.