Various factors have been suggested by Archaeologists for the decline of the Mature Harappan civilisation. Which of the following reasons is correct in this context?

All of the above

The correct answer is Option 4 - All of the above

Causes of the decay of Harappan Civilisation:

Environmental changes, such as climate shifts and river course alterations.
Natural disasters like floods, earthquakes, and droughts.
The decline in long-distance trade networks and economic prosperity.
Social and political instability and internal conflicts.
Resource depletion, including deforestation and soil degradation.
Disease outbreaks and epidemics.
Contested theory of an Aryan invasion from the northwest.

In the few Harappan sites that continued to be occupied after 1900 BCE there appears to have been a transformation of material culture, marked by the disappearance of the distinctive artefacts of the civilisation – weights, seals, special beads. Writing, long-distance trade, and craft specialisation also disappeared. In general, far fewer materials were used to make far fewer things. House construction techniques deteriorated and large public structures were no longer produced. Overall, artefacts and settlements indicate a rural way of life in what are called “Late Harappan” or “successor cultures”. What brought about these changes? Several explanations have been put forward. These range from climatic change, deforestation, excessive floods, the shifting and/or drying up of rivers, to overuse of the landscape. Some of these “causes” may hold for certain settlements, but they do not explain the collapse of the entire civilisation. It appears that a strong unifying element, perhaps the Harappan state, came to an end. This is evidenced by the disappearance of seals, the script, distinctive beads and pottery, the shift from a standardised weight system to the use of local weights; and the decline and abandonment of cities. The subcontinent would have to wait for over a millennium for new cities to develop in a completely different region.