Which of the following metals was not known to the people of the Harappan civilization?

Iron

The correct answer is Option 1- Iron

Iron was not known to the people of the Harappan civilization. They did, however, use copper, gold, and bronze.

The Harappan civilization, also known as the Indus Valley Civilization, was a Bronze Age civilization that flourished in the Indus River Valley from around 2500 to 1700 BC. The Harappans were skilled metallurgists and produced a wide range of copper and bronze tools, weapons, and jewelry. They also traded with other civilizations for gold and other metals.

Iron was not discovered until much later, around 1200 BC, during the Iron Age. The Iron Age was a period of rapid technological and social change, as iron tools and weapons were far superior to those made from copper or bronze.

The Harappan civilization declined around 1700 BC, and it is not clear why. Some scholars believe that the decline was due to climate change, while others believe that it was due to overgrazing or deforestation.

The discovery of iron was a major turning point in human history. It led to the development of new tools and weapons, and it also led to the rise of new civilizations.