Explanation:

- The concept of the four Ashrams - Brahmacharya (student life), Grihastha (householder life), Vanaprastha (forest-dweller/hermit life), and Sannyasa (renunciate life) - is rooted in the ancient Indian texts.

- They represent the ideal stages of life according to Hindu philosophy.

- Purusha-Sukta: This is a hymn from the Rigveda, majorly focusing on the cosmic being, Purusha. It does not directly discuss the Ashrams.

- Atharvaveda: One of the four Vedas, it primarily contains hymns and mantras, but is not the specific source for the Ashrams.

- Later-Vedic Phase: Refers to the period where development in philosophical ideas occurred, but it is broader and not specifically linked to the concept of Ashrams.

- Jabala Upanishad: This Upanishad specifically discusses the concept of the four Ashrams.

- Answer: Option 4 - Jabala Upanishad