Question

Which are thought to have contributed to the decline of the Indus Valley civilizations?
A. Indus Valley populations migrated to Central Asia and Africa.
B. Volcanic eruptions covered the land with molten lava.
C. Centuries of floods made the soil salty and unfit for farming.
D. The surrounding land was severely deforested.
E. Diseases reduced the population.

Answer 1

disease reduced population

Answer 2

The reasons which have contributed to the decline of the Indus valley civilization are the volcanic eruptions which covered the land with molten lava and centuries of floods which made the soil salty and unfit for farming.

The theory of a tremendous climatic change or catastrophic event picked up validity.

It has been discovered that around 2000 BC some major climatic changes began happening in the Indus Valley.