The civilization that traded with India during the 1400s is the Swahili Coast. The Swahili Coast was a significant trading region along the East African coast, and it engaged in trade with various regions, including India, through maritime routes.
The other options listed—United States, Axum Empire, and Britain—did not engage in trade with India in the same context during the 1400s. The Axum Empire was historically significant, but it had largely declined by that time, and Britain’s significant trade activities with India occurred later, particularly in the 17th century and onwards. The United States did not exist as a nation in the 1400s.