90% of the dentists we surveyed state that they prefer

Responding to a pm:

Alarms should start ringing whenever you see percentages in a GMAT critical reasoning question, as percentages require context that CR stimuli almost never supply. In this case, 90% sounds great, but if that 90% means 90% of 10 incompetent dentists or 90% of 100 bribed dentists it isn’t a very impressive figure, is it? If we don’t know what sample that 90% comes from, we can’t say if it’s a resounding endorsement of Galactico gum, so (A) is the best answer here.

(B) is not correct. The problem with the argument is not "Great taste and great dental health need not go together."
The argument does not say that great taste and great dental health should go together. It only says that in this product, they do go together. The commercial gives you premises that give support to dental health and then tells you that the gum has taste and health benefits so if you want those, go for the gum. It doesn't imply that great taste comes automatically with great health. Just that in this product, both are present.