What indicates that the author's purpose is to inform readers about travel south of Madagascar and Zanzibar?

The answer is: The author shares facts and specific details about the difficulty of sailing in the region.

In the excerpt from "The Travels of Marco Polo," the narrator describes the great effort required to sail south of Madagascar and Zanzibar. The reason is the course of water flows so strongly to the south, that ships cannot return or take three months to go back.

The rest of the options are incorrect because the author does not include any dramatic stories or uneasiness about the animals in the region. He does not express any opposition as regards sailing in the area either.