What were some of the reasons which lead to the Decline of the Indus Valley Civilization?

The correct options are
A Overpopulation
B Overgrazing
C Deforestation
D Posiible invasion

Increasing population made the administration difficult. Garbage piled up on streets, drainage systems broke down, and houses were built on roads. Too much grazing by their plentiful herds destroyed the green cover. Increasing demands of wood for fuel led to deforestation. The Aryans also invaded India.