Explanation:

Both the Amazon Basin in South America and the Congo Basin in Africa are renowned for their extensive tropical rainforests, which thrive in regions characterized by high temperatures and abundant rainfall throughout the year. These climatic conditions are typical of the Equatorial belt, which lies roughly between $5^\circ \text{N}$ and $5^\circ \text{S}$ latitude. Option A, the Mediterranean belt, is characterized by dry summers and mild, wet winters, which is climatically distinct. Option C, the Tropical monsoon belt, experiences distinct wet and dry seasons, unlike the consistently wet equatorial climate. Option D, Monsoon belt, is a broader term, but 'Equatorial belt' (B) precisely describes the geographical and climatic zone where these two major basins are situated, making it the most accurate choice.