Question

What allowed Native Americans in Mexico to settle cities larger than those in areas to the north?

Answer 1

A. The use of advanced engineering methods learned in Asia
-this is not true. At the time of the migration from Asia to America via the Bering Strait, the technology wasn't this developed yet

b. The requirement of their religion to have large cities
-this is not true: there wasn't such a requirement

c. The use of farming to feed a larger population
-This is also not true: farming was common i North America and also in some parts farming was not necessary as there was a plenty of food without it (for example through fishing).

d. The development of cities that were built by an earlier civilization 
-this is the best answer! Mesoamerica has a very long history of civilizations, and the cities grew larger and larger with time.