A. prison and asylum reform
Cahokia was one of the largest and possibly the capital city of the people that are referred to as the Mound Builders. Cahokia's size and the large number of people that lived there led to the main issues. Bad droughts and poor harvests meant people couldn't eat.
Civilizations developed around rivers because their waters provided places to hunt and fish.
Also, as the rivers flooded, the lands around them became fertile. This allowed them to support farming.
In addition, because they provided a steady supply of drinking water.
Moreover, goods and people could be transported easily
Finally, River valleys not only have water, they also often have a broad, flat floodplain that is readily adapted to agriculture.
I believe that the correct answer is D.)Animal Species
Animals reproduce , breed , and affect the agriculture.
Look up the word agriculture , you will see how my answer makes more sense.
My reason being is mainly because everything basically lives off of animals and if the are affected by anything and in any way start to decrease , the population will also.
I really hope that this helps you out a lot.