The correct answer is Option 1- Archaeological Excavations

The main source of information about the Indus Valley Civilisation is archaeological excavations.

The Indus Valley Civilisation, also known as the Harappan Civilisation, was one of the first urban civilisations in the world. It flourished in the Indus River Valley region of what is now Pakistan and India from around 3300 to 1300 BC.

Very few written records have been discovered from the Indus Valley Civilisation, and the Indus script remains undeciphered. This means that archaeologists have had to rely on physical evidence from archaeological excavations to learn about this ancient civilisation.

Archaeologists have excavated many Indus Valley Civilisation sites, including the major cities of Harappa and Mohenjo-daro. These excavations have revealed a wealth of information about the Indus Valley Civilisation, including its urban planning, architecture, drainage system, pottery, metalworking, and trade networks.