How is the water polluted?

(Higher-order thinking)

Shihab and Kaniz see people bathing, washing clothes, and throwing kitchen rubbish in the river.

They see a man throwing some kitchen rubbish into the river. It pollutes the water. So, they feel upset.

They see some polythene bags, plastic bottles and some other things floating on the river.

Fish cannot swim easily in dirty water. They get caught into polythene bags. So their lives are in danger.