Which source of pollution is covered indirectly by the soil and water resources conservation act but excluded from the clean water act?

The correct answer is Agricultural runoffs.  

A United States federal law, which monitors the emission of pollutants into the surface water of the nation, comprising rivers, lakes, wetlands, streams, and coastal regions is known as the Clean Water Act. It came into force in 1972 and got amended in 1977 and 1987.  

Of the mentioned options agricultural runoffs are excluded from the Clean Water Act but is covered indirectly by the Soil and Water Resources Conservation Act.  

the answer would be c