What was the primary motivation for the draining of lake beds in Mexico City? A. to reduce the risk of flooding B. to prevent the spread of diseases C. to protect the city from invaders D. to mine for gold under the lake beds

The correct answer is A. to reduce the risk of flooding. Floods can be just as dangerous as fires or tornados or similar things and can not only kill people, but also completely ruin the economy by ruining things like crops or businesses or manufacturing plants. That's why Mexico City has drained the lake beds.