Answer:
Spreading axis
Explanation:
Oceanic crust is constantly being pushed horizontally away from the ridge crest toward an oceanic trench. This ridge crest is known as spreading axis or spreading center. The phenomenon itself is known as seafloor spreading. Seafloor spreading as a theory was first proposed by Harry Hess in 1962. He proposed that sea floor moves, as well as continents. The seafloor moves at a rate of about 1-24 cm per year.
I belive the answer to the first one is no I would have to assume a habitual zone is one area on a planet. for example, an air conditioned building vs. the Savvanah dessert. However I am not sure maybe other answers will help more on this one. Sorry.... Earth-like planet would of course need water, plant life, animals, oxygen, fossil fuels etc. A challenge we would face on a travel to another liveable planet: do we have engough transportation? engough fuel to make it? How long can we live on this planet? Who or what else is present here? etc. Yes I do think they should discover a planet with earth like qualities befor investing in tools to get us to them. So money is not wasted. (make sure to put this into your own words )
It is B pair the last one
