Question

Which of the following is a negative externality of creating a hydroelectric dam on a major river?

A. Lakes for tourists

B. Energy creation

C. Improved flood control

D. Environmental impact

Answer 1

the one that regarded as a negative externality of creating a hydroelectric dam on a major river is: D. Environmental impact

Installing Hydroelectric dam in the major river will change the chemical composition of the ecosystem in that area.
This will heavily affect the biodiversity in that ecosystem 

Answer 2

I agree it's D , I got it right