Why Were So Many People Killed by the 2010 Haitian

Why were so many people killed by the 2010 Haitian earthquake?

A) Haiti has never had any previous earthquakes.
B) The earthquake hit the most densely populated area of Haiti and buildings were not constructed to withstand earthquakes.
C) Most of the fatalities were due to a tsunami.
D) Most people died because of landslides.
E) Most people died in flooding that followed the earthquake.