Final answer:
Papua New Guinea is not in Africa; it is part of the Australasia region. Great Zimbabwe, also not in West Africa, was an empire in Southern Africa. Hence, the correct answer is option D.
Step-by-step explanation:
The country that is not in Africa among the options provided is D. Papua New Guinea. Papua New Guinea is located to the north of Australia and is part of the region known as Australasia, which also includes Australia and neighboring islands in the Pacific Ocean. On the other hand, Guinea-Bissau, Guinea, and Equatorial Guinea are all countries located on the African continent.
When it comes to historical empires, the Great Zimbabwe Empire was not in West Africa. It was located in present-day Zimbabwe, which is in Southern Africa. The Ghana, Mali, and Songhay empires, however, were all significant empires that existed in West Africa.