The option that best describes the difference in the geographic extent of the Ghana Empire and the Songhai Empire is:
The Songhai Empire controlled more of the Niger River and area in the Sahara Desert.
This statement accurately reflects the fact that the Songhai Empire, at its height, expanded further along the Niger River and into the Sahara Desert compared to the earlier Ghana Empire, which was primarily located in the regions that are now southeastern Mauritania and western Mali.