Earthquakes are common in Mexico because of most of the land mass being on the North American plate and the Ocean floor being on the Coscos plate and so when the more dense ocean floor plate goes up and hits the North American plate it goes up under the more finer granite part of the North American plate and if you were to push something heavy across the table you'll notice it kinda creates a shaking this is what's happening under the plates.
B; la escalera translates to the escalator, which are the moving stairs in malls and stores that people use to go from one floor to another. You can't use the first floor, garage, or basement to go to another floor.
La clase de siencas es mucho mejor que la clase de mathematicas.
Seinca es la moejor clase de la escuela.