An earthquake of 7.1 occurred in mexico city. in this case the of this earthquake would be located in mexico city.

The EPICENTRE of the earthquake would be found in Mexico City. The epicentre is the point directly above the focus of an earthquake on the earth's surface. The focus is the point beneath the earth's surface where the rocks break during an earthquake. The focus is always quoted as kilometres beneath the earth's surface and the epicentre is always referred to as a proximity to a place on the surface (town or city). 

It should be d if not then c