The correct answer is letter D.
The letter that identifies the location of the Aztec civilization on the map is letter D.
I have attached the map, for a better understanding.
The Aztec civilization was one of the most important cultures in Mesoamerica, before the arrival of the Spanish conquerors. They inhabited the territories of central México. Its capital city was the great Tenochtitlan, built above the Texcoco lake, in what today in downtown Mexico City.