How the Indus valley civilization declined? Give correct reasons contributed to the

Q. How the Indus valley civilization declined? Give correct reasons contributed to the decline of civilization.

1. Due to fall in foreign trade continuously

2. Due to changing monsoon, the scarcity of rains.

3. Due to ruling of weak foreign powers.

4. Due to the animals used the pasturs in excess.

Which of the above is / are correct

(a) 1 and 4

(b) 1, 2 and 4

(c) 2, 3 and 4

(d) 2 and 3

Ans: (b) 1, 2 and 4