The statement that best describe the achievement is that the Sunni Ali unified the empire through military conquest.
Who was Sunni Ali?
Sunni Ali was born in Ali Kolon and is also known as Si Ali and Sunni Ali Ber. He was king that served from the year 1464 to 1492.
Sunni Ali was the 15th mortal or ruler of the Sunni dynasty and the first king of the Songhai Empire in Africa. Many cities, considering Timbuktu and Djenné, were taken and fortified under Sunni Ali's command.
His most of his achievements were mainly military so, He unified the empire through military conquest.
Therefore, option B is correct.
Learn more about the Sunni Ali, refer to:
https://brainly.com/question/25280064
#SPJ2