This is because water breaks down stuff that is slightly fragile if you have enough of it. It can easily break down stuff like rocks. That likely caused a lot of canyons and craters on the Earths surface. Plus, it couldn't be the first option due to most asteroids not being able to make it onto Earths surface. (At least not to were there big enough to cause canyons). It's not the option 3 because earthquakes occur on Earths surface and does not affect Earths core. And finally, its not the final option, because there is no possible way for magma deep in Earths core to make its way to the surface, thanks to gravity. Therefore, the only option it could possibly be is the second option, which is your answer.
