Why is C correct?

Could someone explain this question to me?

@Shiyi-Zhang, Happy to help. The question says, "The author mentions that 'Byron's literary craftsmanship is irregular' (lines 27-28) most probably in order to..." We're looking for the function of the phrase in the text. In order to answer this question correctly, we need to look at the text surrounding lines 27-28. The second paragraph begins by stating Byron is not a 'great' poet, as evidenced by the fact that most of Byron's poems cannot be convincingly read as subtle verbal creations. Then, the author says, "It must be admitted too that Byron's literary craftsmanship is irregular, and often his temperament disrupts even his lax literary method." In saying this, the author is mentioning that Byron's literary craftsmanship is irregular to provide further support as to why Byron is not a 'great' poet. Now that we've identified why the author mentions the phrase in question, let's look at the answers. (C) says the author mentions the phrase to "offer another reason why Byron is not a 'great' poet." This is precisely what we had anticipated the correct answer saying, so it's the right choice, as it accurately describes the function of the phrase in the passage. Does this make sense? Let us know if you have any more questions!