The correct option is A respected woman who had attained liberation..
Explanation
The Buddhist Sangha was organized into an order of monks (Bhikkhus) and nuns (Bhikkhunis). Within this monastic structure, specific terms were employed to denote the seniority and spiritual status of its members.
Detailed Analysis:
- The term Theri (Pali for "elder woman") specifically refers to respected women within the Sangha who had grown old in the practice of the Dhamma and had attained liberation (Nirvana).
- These elder nuns were distinguished by their spiritual achievements. Their verses, expressing their struggles and enlightenment, are preserved in the Therigatha, a text within the Pali Canon.
- A new entrant to the order. is incorrect: A new entrant or female novice in the order is referred to as a Samaneri.
- A female lay follower. is incorrect: A female lay follower who supports the Sangha but remains in the household life is known as an Upasika.
- A special robe worn by nuns. is incorrect: While nuns wore monastic robes (Civara), the term Theri denotes the person and their status, not the garment.
Key Takeaway: In Buddhism, a Theri is a senior nun who has attained spiritual liberation, distinct from a novice (Samaneri) or a lay devotee (Upasika).