The correct answer is: a) Rice cultivation.
Majuli is the largest river island in the world, located in the Brahmaputra River in Assam, India. It is known for its unique culture and traditions, as well as its natural beauty. The island is home to a number of Vaishnavite monasteries, known as sattras, which are important centers of learning and worship. Majuli is also a major rice-producing region, and its agricultural practices have been recognized by UNESCO as a Masterpiece of the Oral and Intangible Heritage of Humanity.
Option b) is incorrect because Majuli is not known for its wildlife sanctuary. The island is home to a variety of wildlife, including tigers, elephants, and deer, but there is no designated wildlife sanctuary on the island.
Option c) is incorrect because Majuli is not known for its tea plantations. There are a few tea plantations on the island, but they are not a major economic activity.
Option d) is incorrect because Majuli is not known for its tea plantations. There are a few tea plantations on the island, but they are not a major economic activity.