To accurately determine which letter identifies the location of the Maya civilization, it's important to know that the Maya civilization primarily occupied parts of modern-day Mexico (specifically the Yucatán Peninsula), Guatemala, Belize, Honduras, and El Salvador.
In a typical map where the region is marked with letters, the letter that corresponds to this area is likely the letter that is positioned near the Yucatán Peninsula and Central America. Based on your description, the correct identification would be one of the letters denoting the region around that area.
If I had to choose based on standard map conventions, the most likely answer would be A or D, as they could geographically correspond to the region of the Maya civilization. However, without seeing the actual map, I cannot definitively specify which letter it is. Please refer to the letter that is positioned in the area of the Yucatán Peninsula and much of Central America.