Answer : 4. "कांस्य युग"
Explanation :

The Harappan civilization belonged to the Bronze Age. The Bronze Age is a historical period characterized by the widespread use of bronze, the appearance of written materials, and the early beginnings of urban civilizations. It extended from approximately 3300 BC to 1200 BC. The Harappan civilization flourished around 2500 BC – 1500 BC.