Which detail best supports the author's argument that Glen Canyon would be

better off without the dam?

Answer: B. Plant life cannot grow along the shoreline.

Explanation:

In the extract from Beyond the Wall: Essays from the Outside, Edward Abbey, the author, argues that it is because of the dam that plant life is dead. He says that due to the fluctuations in the water level, the plants either die from thirst or get drowned. This to him, is a stark contrast to when the area used to be full of plant life which also brought animal life meaning that there was an abundance of both fauna and Flora.

Now instead, the area is barren and Edward contends that it would therefore had been better that the dam was not built at all than it was built and effected the aforementioned.