The correct option is C Advaita
Shankara was very intelligent. At the age of seven, he had mastered all the scriptures. He learnt the Vedas and the Puranas. He studied the Upanishads and the Brahmasutras in depth and propagated the Advaitha philosophy which says that Brahma is the absolute truth. It has no qualities, no features and no shape. The rest of the world is false. The soul is one with Brahma and life is not separate from Brahma. The world is maya, an illusion. People are ignorant. Hence, we should go on the path of knowledge and realize the nature of the world. Ultimately, we should merge our 'atma' (soul) with the absolute truth, Brahma which will help us in attaining salvation. His hymn Bhajagovindam is world famous. Shankaracharya travelled from Kanyakumari to Kashmir on foot and propagated his Advaitha philosophy.