Upaniṣads, Bhagavadgītā and Brahma Sūtrās are put together nameda.Vijñāna-Trayab.Āsthāna-Trayac.Prasthāna-Trayad.all of these

The Upaniṣads, Bhagavadgītā, and Brahma Sūtrās are collectively referred to as Prasthāna-Traya. This term translates to "the three texts that form the basis or foundation" of Vedanta philosophy.

1. Upaniṣads: These are ancient Sanskrit texts that contain some of the central philosophical concepts and ideas of Hinduism.
2. Bhagavadgītā: A 700-verse portion of the Indian epic Mahabharata, it is a conversation between Prince Arjuna and Krishna, who serves as his charioteer, addressing complex issues of duty, righteousness, and the nature of reality.
3. Brahma Sūtrās: A concise and systematic compilation of the philosophical teachings of the Upaniṣads, aiming to clarify the key concepts of Vedanta.

In summary, the correct answer is c. Prasthāna-Traya.