Final answer:
The impact of the savanna on the people of Africa is best described by their use of the region for farming, which has supported civilizations and contributed to the development of kingdoms over centuries.
Step-by-step explanation:
Among the provided options, the correct one that explains the impact of the savanna on the people of Africa is that people farmed in the savanna. The savanna is not devoid of life; rather, it is teeming with various species of flora and fauna. Also, the question of people not being able to cross the Sahara is not directly related to the savanna but rather the Sahara itself. Therefore, the most accurate option that describes the relationship of the savanna with the people is their use of it for farming.
Africa's savannas are rich in biodiversity and offer fertile grounds due to seasonal rains, although their soils are not as productive as those in well-watered regions. Still, over centuries, they have supported the growth of impressive civilizations, as evidenced by the centuries-old farming practices along the Niger River, and played a vital role in the development of medieval West African kingdoms. The savanna biome, with its mixed landscape of grassy plains and scattered trees, has hosted more human history than any other part of the continent, providing food, shelter, and a means of subsistence through both agriculture and animal herding.