The correct answer is B. Sankara.
Sankaracharya was an Indian philosopher and theologian who lived in the 8th century CE. He is considered one of the most important figures in Hindu philosophy and is credited with establishing the Advaita Vedanta school of thought. Advaita Vedanta is a non-dualistic philosophy that teaches that Brahman, the ultimate reality, is the only thing that exists. All other things, including the individual self, are illusory.
Sankaracharya’s teachings had a profound impact on Hinduism and continue to be influential today. He is considered one of the most important teachers in Hindu history and his teachings are still studied and practiced by millions of people around the world.
Ramanuja was a Hindu philosopher and theologian who lived in the 11th century CE. He is considered one of the most important figures in the Visistadvaita school of thought. Visistadvaita is a qualified non-dualistic philosophy that teaches that Brahman, the ultimate reality, is both one and many. The individual self is not an illusion, but is a part of Brahman.
Guru Nanak was the founder of Sikhism, a monotheistic religion that originated in India in the 15th century. He is considered the first Guru of Sikhism and his teachings are still followed by millions of people around the world.
Chaitanya was a Hindu saint and mystic who lived in the 16th century CE. He is considered one of the most important figures in the Gaudiya Vaishnava tradition. Gaudiya Vaishnavism is a devotional movement that worships Vishnu, one of the principal deities of Hinduism.
In conclusion, the correct answer to the question is B. Sankara.