Concept:By the end of the 18th century, Ottoman Turkey maintained the strongest imperial presence across the northern half of Africa.
Explanation:The Ottoman Empire controlled key North African territories through its dependencies.
These included Egypt, Tripoli, Tunis, and Algiers.
Although these regions were largely self-governing, they still recognised Ottoman authority and paid some revenue to the sultans in Istanbul.
No other European power, including Portugal, held such widespread control in this area at that time.
Therefore, Ottoman Turkey was the only significant imperial power in the northern half of Africa.
Answer:A. Ottoman Turkey