Final answer:
Bar Harbor, Maine, is located on Mount Desert Island, which is the correct answer to the student's question and is option D.
Step-by-step explanation:
The town of Bar Harbor in Maine is located on Mount Desert Island. This island is the largest off the coast of Maine and is notable for its picturesque landscapes, including Acadia National Park. Answering the student's question, the correct option is D) Mount Desert Island.