One of the major motivations for altering the environment in mexico city was a. creating arable land b. reducing population growth c. providing recreational opportunities d. reducing dependence on agriculture

It's option A, not B. I just took the test.

One of the major motivations for altering the environment in Mexico City was creating arable land (A).

The altering of the environment in Mexico City refers to the draining of Lake Texcoco. It was done because the city experienced severe flooding, but also in an attempt to create arable land. However, many parts of the valley are now semi-arid and the area still suffers from lack of water.