How does the hydroelectric dam pictured here impact the environment?

a. by generating significant heat that artificially warms nearby water
b. by producing greenhouse gases
c. by releasing toxic chemicals in their emissions
d. by blocking fish migration

D. By blocking fish migration.

Explanation:

The pictured waterfalls are artificial.

The construction of the wall to raise water level for the falls to be created cuts the contact between marine organisms.

The fish on the other end of the fall cannot freely migrate to the other side.

This is because the falls are too dangerous for them and can lead to their death.

This means that the pictured method of power generation is not environmental friendly.

i think that d. wind is the answer.   i missed the question when i answered a. currents.