Madagascar is the largest island in the Indian Ocean, making option B the correct answer. Here's an explanation of why Madagascar is the largest island in the Indian Ocean:

Geographical Location:
- Madagascar is located off the eastern coast of Africa, in the southwestern part of the Indian Ocean.
- It is the world's fourth-largest island and covers an area of approximately 587,041 square kilometers.
- The island is surrounded by the Mozambique Channel to the west, the Indian Ocean to the east, and the Coral Sea to the north.

Size and Population:
- The large size of Madagascar contributes to its status as the biggest island in the Indian Ocean.
- With a length of around 1,580 kilometers and a width of approximately 590 kilometers at its widest point, Madagascar has a diverse range of landscapes and ecosystems.
- The island is home to a rich biodiversity, including unique species of flora and fauna found nowhere else on Earth.
- Madagascar has a population of over 26 million people, making it the world's 47th most populous country.

Political and Economic Significance:
- Madagascar is an independent country and has its own government. It is not part of any other nation or a group of islands.
- The capital city of Madagascar is Antananarivo, and the official languages are Malagasy and French.
- The country's economy is largely based on agriculture, with key exports including coffee, vanilla, cloves, and seafood.
- Tourism also plays a significant role in the economy, as visitors are attracted to Madagascar's unique wildlife, national parks, and stunning landscapes.

Rich Natural Resources:
- Madagascar is known for its rich natural resources, including minerals such as graphite, chromite, and ilmenite.
- The island also has significant reserves of bauxite, coal, and gemstones.
- These resources contribute to Madagascar's economy and have the potential for further development and exploitation.

In conclusion, Madagascar is the largest island in the Indian Ocean due to its significant size, diverse landscapes, rich biodiversity, and economic significance.