The answer is C genetic variation
There are four nitrogenous bases involved.
A, T, C and G.
A:T and C:G
Watershed is the place where water of rain and snow get stored. The watershed contains surface water-and wetlands--and all the underlying ground water,lakes, streams, reservoirs. Lake is the major component of the watershed . The watershed can be used for various purpose like dams, hydrological modification etc.
Through electrochemical processes