Parkour is an exhilarating, yet sometimes dangerous, sport.

why are commas, rather than dashes or parentheses, used in this sentence?

a.

commas are being used to set off an appositive.

b.

commas are being used to set off a clause using which, who, whom, or whose.

c.

commas are being used to set off a longer or less-related parenthetical aside.

d.

commas are being used to set off a brief, closely-related aside.

The correct answer is D. Commas are being used to set off a brief, closely-related aside.

Explanation:

In grammar, an aside refers to a word or set of words that act as a subordinating clause, this means the words depend on the main sentence to have a complete meaning. Asides can be marked using parentheses, dashes or commas; however, in the case the aside is short and closely related to the sentence comms are preferred as parentheses or dashes introduce a more drastic break that is not necessary if the aside is short.

This occurs in the case of "Parkour is an exhilarating, yet sometimes dangerous, sport" because the aside "yet sometimes dangerous" is too short and it is closely connected to the sentences, therefore using commas is better. Thus, commas are used because "Commas are being used to set off a brief, closely-related aside".