The correct answer is the following.
The Aztecs were farmers.
They indeed were great farmers. And you would ask yourself how if they lived on a lake. The Texcoco lake. Well, they were also great engineers. They built what they called the Chinampas with mounts of mud to have portions of solid land where they grew crops and flowers, products that later were traded in the Tlatelolco market in north Tenochtitlan. Aztecs grew tomatoes, corn, cacao, chile, and beans.