I believe the answer is B.
If the Moon were to double in mass, the gravitation force between it and the Earth would <u>become</u><u> </u><u>twice</u><u>.</u>
It's an animal cell because it doesn't have a cell wall or chloroplasts. It's also not rectanglular shaped. :)
Okay. The destruction of tundra vegetation will not really freeze the soil or deepen the active zone much. Therefore, A and C are eliminated. The destruction of the vegetation can actually melt permafrost, which contributes to global warming. The answer is D.