Question

how were the olmec able to support a civilization and cities?
by implementing heavy taxes to raise public funds for communities
by constructing residential dwellings for their growing populations
by cultivating a surplus of food to feed a large population
by developing a system of roadways to connect the cities

Explanation:

The Olmec civilization's ability to support cities relied on food surplus. Tax systems (first option) aren't typical of Olmec, road systems (fourth) and residential construction (third) don't directly support civilization growth like food surplus (second option) does, as agriculture and surplus allowed population growth and urban development.

Answer:

By cultivating a surplus of food to feed a large population