Which is one theory about what caused the decline of the indus valley civilization

Answers:

The soil became too salty for crops to grow

Earthquakes in the himalayas caused massive destruction

Merchants and traders stopped coming into the valley

Diseased animals created food shortages for the people

1. Incorrect. This is not a cause by itself. It would be the result for another circunstances, for example changes in the structure of the river, quality of rain water or types of farming.

2. Correct. This could be a possible cause. Geological movements in the nearby mountain systems could cause changes in the course of the rivers and with it, the desertification and the fall in disuse of the water systems, drainage and irrigation of the city.

3. Incorrect. This is not a cause. This could be the consequence of the decrease in the quality or quantity of the products they used for trade, both agricultural and ceramic or some difficulty in the means of transport that linked them to trade routes.

4. Incorrect. Animal diseases could not be a cause, but a consequence of something more serious on an environmental scale. Having the ability to trade, the death of animals could have determined a momentary change in their eating habits, but no more.

The correct answer is that the soil became too salty for crops to grow, which led to the decline of the Indus Valley civilization. The drought caused by this salinity generated a great decrease in the commercial capacity of this civilization against the Egyptians and Mesopotamians, who where de facto those who supported the consumption of the Indus civilization through the exchange of goods.