Long ago our rivers were fresh and clean, so clean that people drank the river water. Those rivers were full offish. People caught and cooked them. In time people built factories and towns that used the river water. Boats are used to carry goods and coal and oil, which sometimes falls into the water. People throw their garbage and dirty water into the rivers. They say, "Our garbage cannot make much difference".
But now the rivers have become too dirty to drink from and the fish have died. The rivers are now full of garbage that floats on the water.
What happened first?

Options

A. Fish were gone from the rivers.
B. Factory boats came down the rivers.
C. The rivers were clean and beautiful.
D. Towns built more and more factories.

Answer

C