The correct answer is B. M. S. Swaminathan was an agricultural scientist. He was a pioneer in the field of agricultural research and development, and his work has had a major impact on the lives of millions of people around the world. He is best known for his work on the Green Revolution, which helped to increase food production in India and other developing countries. He was also a strong advocate for sustainable agriculture, and he worked to promote the use of environmentally friendly farming practices.
Option A is incorrect because M. S. Swaminathan was not a journalist. He was an agricultural scientist.
Option C is incorrect because M. S. Swaminathan was not an ecologist. He was an agricultural scientist.
Option D is incorrect because M. S. Swaminathan was not an ornithologist. He was an agricultural scientist.