Explanation:

- Option 1: Ashoka Pillar

- These are columns erected by Emperor Ashoka during his reign in the 3rd century BCE.

- Known for their inscriptions and the "Lion Capital", which is India's national emblem.

- They are historical markers, but not inscribed as World Heritage Sites collectively in 2016.

- Option 2: Ellora Caves

- Located in Maharashtra, not Bihar.

- Known for rock-cut architecture and religious structures.

- Recognized as a World Heritage Site, but not in 2016.

- Option 3: Sanchi Stupa

- Situated in Madhya Pradesh, not near Patna.

- A Buddhist complex famous for its Great Stupa.

- Listed as a World Heritage Site long before 2016.

- Option 4: Nalanda Mahavihara

- An ancient monastic university located near Patna in Bihar.

- Inscribed as a UNESCO World Heritage Site in July 2016.

- Known for its significant historical and cultural impact in ancient India.

Option 4: Nalanda Mahavihara is the correct answer.

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