The ancient Harwan complex showcases remains of:

Buddhist and Hindu structures
Roman settlements
Greek trading posts
Persian palaces

The correct answer is: a) Buddhist and Hindu structures.

The Harwan complex is an archaeological site located in the Baramulla district of Jammu and Kashmir, India. It is a group of ruins of Buddhist and Hindu structures dating from the 2nd century BCE to the 6th century CE. The complex is spread over an area of about 100 hectares and includes temples, monasteries, stupas, and other religious buildings.

The Harwan complex is one of the most important archaeological sites in Jammu and Kashmir. It is a UNESCO World Heritage Site and is a popular tourist destination.

The other options are incorrect because:

  • Option b) is incorrect because there is no evidence of Roman settlements in Harwan.
  • Option c) is incorrect because there is no evidence of Greek trading posts in Harwan.
  • Option d) is incorrect because there is no evidence of Persian palaces in Harwan.