The correct answer is: C. AD 1517.
Gurudwara Pathar Sahib is a gurdwara located in the village of Paonta Sahib in Himachal Pradesh, India. It is one of the five takhts, or seats of temporal authority, of Sikhism. The gurdwara was built in 1517 by Guru Nanak Dev Ji, the first Guru of Sikhism. It is said that Guru Nanak Dev Ji meditated at this spot for 40 days and nights. The gurdwara is built on a rock, hence the name Pathar Sahib.
The gurdwara is a popular pilgrimage site for Sikhs. It is also a popular tourist destination. The gurdwara is open to all visitors, regardless of religion.
Option A: AD 1000 is incorrect because Guru Nanak Dev Ji was born in 1469.
Option B: AD 1200 is incorrect because Guru Nanak Dev Ji started his preaching mission in 1499.
Option D: AD 1600 is incorrect because Guru Hargobind Ji, the sixth Guru of Sikhism, was born in 1595.