D. Next
The words first, during, next<span> and </span>finally<span> tell in what order the events happened.
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Answer
Tanks, machine guns and poison gas
Explanation:
The main factor was the utilization of raised field agriculture. They would build these fields that had been artificially raised to a certain height along a flowing water source (mostly rivers but occasionally streams as well in some cases). When tropical weather patterns would cause said water sources to flood, instead of washing away the crops, it would act as irrigation for the raised fields. Securing a steady food source allowed the Mayans to support a large civilization in the tropical regions they called home.
