Final answer:
Landform F on the map, an island in the Indian Ocean, is the island of Madagascar.
Step-by-step explanation:
On the map provided, the name of landform F, which is an island in the Indian Ocean, is the island of Madagascar. This makes C the correct answer from the provided options. The Great Rift Valley is a continuous geographic trench, approximately 6,000 kilometers in length, and the Horn of Africa refers to the easternmost extension of the African continent. The Sahel is a transitional zone between the Sahara desert to the north and the savannas to the south.