Option a is the correct answer. Nagarjuna was a 2nd-century Indian Buddhist philosopher who is considered to be the founder of the Madhyamaka school of Mahayana Buddhism. The Madhyamaka school is a non-dualistic school of thought that emphasizes the emptiness of all phenomena. It is a collection of 27 chapters that present Nagarjuna's arguments for the emptiness of all phenomena. Important Tips Features of Madhyamaka School: According to Mahasanghikas, Buddha was transcendental, eternal, and infinite. Buddha's teachings are characterized as 'Madhyama Pratipad'. Nagarjuna developed his philosophical treatise known as Madhyamika Karika (Shastra). Madhyamika Karika consists of 27 chapters and contains 448 sutras. The Madhyamika dialectic and philosophy are known as 'Prajna Paramita'. Followers of Nagarjuna's philosophy are referred to as Madhyamikas.