Ais two or more atoms joined together.
a) cell
b) tissue
c) molecule
d) particle

A molecule is two or more atoms joined together.

hope this helps!

i dont have a visual in front of me, but i can you reason to try to get the right one. the graph should look like this, 0 to 6 there is a spike, 12 to 14 there should be a very low point. slight increase in the graph at 12 to 14, and flat 14 to 18

explanation: