Well, due to Hitler invading many countries, those countries did not have big enough armies to defend their country. So when Britain and France tried to attack, they needed help. Which then led to the US being allies, to join in and provide back up.
I'd say A. after a volcanic eruption because mudflows occur mostly on steep slopes where there's little to no prevention of rapid erosion.
Brain and heart brain because we need that to think and to function and we need a heart so you coulod be alive
