Answer: C
Explanation: Earth's atmosphere isn't very dense because it is made of air, which floats. Human beings are denser then air since they are solid, but not as dense as Earth's crust, which is rocky and the densest out of the three.
Answer:
By eating things with protein in it. Sorry if this sounds too simple, but that's all it is.
Sepals help plant production by reproduction through asexual reproduction to be exact.
