Explanation:

3rd option is correct.
Nagarjuna Shunyavada is expounded in Madhyamika.
Madhyamika, important school in the Mahayana (“Great Vehicle”) Buddhist tradition. Its name derives from its having sought a middle position between the realism of the Sarvastivada (“Doctrine That All Is Real”) school and the idealism of the Yogacara (“Mind Only”) school.