The correct answer is: The Songhai Empire controlled more of the Niger River and area in the Sahara Desert.
This answer best describes the difference in the geographic extent of the Ghana Empire and the Songhai Empire. The Songhai Empire was larger in size and controlled more territory along the Niger River and in the Sahara Desert compared to the Ghana Empire. This expansion allowed the Songhai Empire to have access to more resources and trade routes, giving them an advantage over the Ghana Empire in terms of power and influence.