B, you need to talk about age
<span>Three of the men who almost made their way down to the Colorado river thought that the "boulders" they saw from below were "taller than the great tower of Seville." It is not Seville, but the Himalayas, that Dutton was thinking of. </span>
Answer:
C. The reflection is difficult to see
The answer is an adverb clause because "have been" is considered an adverb clause...