Final answer:
Trade along the Swahili coast connected the African interior with East Asia by fostering maritime trade routes and facilitating cultural diffusion, utilizing dhows and monsoon winds for navigation. However, the full coastal extent wasn't used due to geographical challenges that hindered trading vessel navigation.
Step-by-step explanation:
The trade along the Swahili coast connected the cultures of the African interior with those of East Asia primarily c) By fostering maritime trade routes and facilitating cultural diffusion. This was achieved through the establishment of powerful city-states along the East African coast that engaged in sea trade with countries across the Indian Ocean. The use of dhows and the understanding of monsoon wind patterns allowed traders from the Swahili city-states to reach areas as far as China and India, bringing goods from the African interior such as ivory, gold, and slaves, and returning with luxury items, thereby enabling an exchange of cultural practices and ideas.
However, the trading ports of the Swahili coast did not extend along the full length of the coast of Africa due to the rough seas near the southern tip and the monsoon winds growing weaker farther south, which made navigation for dhows difficult. The correct answer to the question about the full length of the coast being utilized in the Swahili trade is a) Hostile tribes in the south kept merchants from establishing cities. The trade network that the Swahili city-states participated in set the stage for an interconnected world, integrating the diverse cultures of the African interior with the vast civilizations of East Asia.