Explanation:

Ramanujacharya propounded the principle of Vashistadvaita.

Shankara, also called Shankaracharya, philosopher and theologian, most renowned exponent of the Advaita Vedanta school of philosophy, from whose doctrines the main currents of modern Indian thought are derived. He wrote commentaries on the Brahma-sutra, the principal Upanishads, and the Bhagavadgita, affirming his belief in one eternal unchanging reality (brahman) and the illusion of plurality and differentiation.

Nagarjuna is widely considered one of the most important Mahayana philosophers. Along with his disciple Aryadeva, he is considered to be the founder of the Madhyamaka school of Mahayana Buddhism. Nagarjuna is also credited with developing the philosophy of the Prajñaparamita sutras and, in some sources, with having revealed these scriptures in the world, having recovered them from the nagas (water spirits often depicted in the form of serpent-like humans). Furthermore, he is traditionally supposed to have written several treatises on rasayana as well as serving a term as the head of Nalanda.

Vasumitra put forward a thesis to defend the basic tenet of the Sarvastivada school that entities (dharma) exist in the past and future as well as in the present. According to him, dharmas exist in a noumenal or latent condition in the future until they attain their moment of causal efficacy (karitra) in the present.