LSAT 13 Section 2 #20

[mandrewsf]

I went for C but the correct answer is A. From my understanding of the question, the flaw in reasoning lies in the fact that the author compared one aspect of pretzel and caramel's cavity-causing properties to make an over-generalization of pretzel and caramel's overall cavity causing abilities. A and C were the obvious contenders, and I thought C expressed more fully the flaw in the reasoning than A, but evidently my reasoning was incorrect. Can someone explain this one for me?

Thanks in advance.