Final answer:
The large cat subspecies living on the island of Sumatra is the Sumatran tiger, an endangered species due to habitat loss from human activities such as oil palm plantations.
Step-by-step explanation:
The subspecies of large cat that lives on the island of Sumatra is the Sumatran tiger (Panthera tigris sumatrae). This critical endangered species is part of the rich biodiversity found within the rainforests of Sumatra and Borneo. Efforts to conserve such unique wildlife are ongoing, especially as habitats are threatened by human activities such as the development of oil palm plantations that damage vital ecosystems.