Step 1: Understanding the Concept of Vedanta.
Vedanta, meaning "the end of the Vedas," encompasses the philosophical teachings of the Upanishads. These texts, forming the concluding part of the Vedas, explore concepts like Brahman (ultimate reality) and Atman (individual soul).
Step 2: Analyzing the Options.
- 1. Aranyaka: Texts concerning forest retreat rituals and sacrifices, not directly linked to Vedanta. - 2. Upanishad: This is correct. The Upanishads are the primary texts of Vedanta, focusing on metaphysical and spiritual knowledge. - 3. Samhita: Collections of hymns and mantras, not directly related to Vedanta. - 4. Brahmana: Texts discussing rituals and ceremonies, excluding the philosophical teachings of Vedanta.
Step 3: Conclusion. The correct answer is 2. Upanishad.
Final Answer: \[ \boxed{\text{The correct answer is 2. Upanishad.}} \]