Which one of the the following usages was a post-Vedic development ?

The correct answer is Option 3. The four-fold Ashrama system (Brahmacharya, Grihastha, Vanaprastha, and Sanyasa) was a post-Vedic development, formalizing the stages of an individual's life. While the early Vedic period focused on rituals and the householder's life, the structured four stages only fully emerged in the later Upanishads and Dharmashastras (e.g., Jabala Upanishad).

• Option 1: The Purusharthas evolved over time, but the core values of Dharma, Artha, and Kama were recognized early; only Moksha was emphasized later.
• Option 2: The Varna system is explicitly mentioned in the Purusha Sukta of the Rig Veda (10th Mandala), making it a Vedic, not post-Vedic, concept.
• Option 4: These are Vedic deities; Indra, Surya, Rudra, and Marut are central figures in the Rig Vedic hymns.

Thus, the institutionalized progression through four distinct life stages (Ashramas) represents a specific evolution in the socio-religious framework of the post-Vedic era.