Option c is the correct answer. Belief in the authenticity of the Vedas is the distinctive features of a nastika and astika system in India. The Orthodox school of philosophy also called the Aastika school believes in the authority of Vedas, while the Heterodox school of philosophy, popularly known as Nastika school rejects the principle of authority of Vedas. Important Tips Six orthodox schools of Hinduism: Nyaya:Sage Gautama is the founder of this school. Nyaya school banks upon various pramanas (mechanism of attaining knowledge). It believes that gaining knowledge through the five senses is the sole way of attaining liberation from the cycle of birth and death. Sankhya: Sankhya is the oldest of all philosophies put forth by the sage Kapila. It is a dualistic philosophy with Purusha (soul) and Prakriti (nature) in it. Advaita Vedanta derives its base from Sankhya School. Yoga: The great Sage Maharshi Patanjali systematized and codified the then-existing practices of Yoga, its meaning and its related knowledge through his Yoga Sutras. Emancipation of Purusha from Prakriti by selfawareness through the discipline of body and mind is conceptualized by Yoga. Vaisheshika: It was founded by the sage Kanada. Vaisheshika school deals with metaphysics. It is an objective and realistic philosophy of the Universe. The universe is reducible to a finite number of atoms, Brahman being the fundamental force causing consciousness in these atoms. Purva Mimamsa: It is based on sage Jaimini's Mimamsa Sutras.Purva Mimamsa school believes in the complete authority of Vedas. It emphasizes the power of yajnas and mantras in sustaining the activities of the universe. It states that a human being can attain salvation only by acting in conformity with the principles of Vedas.