What does the author use in this passage to support the idea that the dam has ruined Glen Canyon?
For those who may think I exaggerate the contrast between the former river canyon and the present man-made impoundment, I suggest a trip on Lake Powell followed immediately by another boat trip on the river below the
dam. Take a boat from Lee's Ferry up the river to within sight of the dam, then shut off the motor and allow yourself the rare delight of a quiet, effortless drifting down the stream. In that twelve-mile stretch of living green, singing birds, flowing water and untarnished canyon walls — sights and sounds a million years older and infinitely lovelier than the roar of motorboats — you will rediscover a small and imperfect sampling of the kind of experience that was taken away from everybody when the oligarch and politicians condemned our river for purposes of their own.
A solution
an exaggeration
a description
a cause and its effect