Which logical fallacy is used in the text?
The thing that makes Hassan stand out as a remarkable cellist is that he's a marvelous musician who plays the cello splendidly.

 - appeal to nature: the assumption that natural things are always good
 - circular reasoning: an argument that supports a claim with the claim itself
 - slippery slope fallacy: the false assumption that a small first step will lead to extreme consequences
The text argues that Hassan is a remarkable cellist because he plays the cello well. However, the "evidence" is just a restatement of the claim itself. This illustrates a type of logical fallacy known as circular reasoning.