It would be much better if you attached the chart to find right answer. I suggest you to search the chart and compare all definitons. Then you can consolidate some to get the answer.
A full definite reason that led to the decline of the Indus Valley Civilization is not known, as no reliable resource of that period is available right now. Every conclusion regarding the decline is based upon speculations of historians on what they believe. Through research it is clear that fall of the Harappan Civilization occurred between 1800 BC to 1700 BC(ish). It is highly believed that the Aryans were the next settlers. They were skilled fighters, so their attack might have led to the fall of Harappan Civilization. Even The human remains found during excavation of Indus valley point towards some violent because of their death
Answer:
I am pretty sure it is A.
Explanation:
If not It is C because It is not b that is for sure.
