Final answer:
The sentence contains a dangling modifier, which is present in the phrase 'Pursing their lips' that incorrectly modifies 'the blueberries' when it should be modifying 'the dinner guests'.
Step-by-step explanation:
The sentence 'Pursing their lips, the blueberries were much too sour for the dinner guests' contains a dangling modifier. A dangling modifier is a word or phrase that modifies a word not clearly stated in the sentence. In this case, 'Pursing their lips' should be modifying the guests, not the blueberries, as it logically does not make sense for blueberries to purse lips. The phrase 'pursing their lips' is intended to describe the guests' reaction to the sour blueberries but is misplaced, leading to a confusing sentence structure. The correct sentence would be 'Pursing their lips, the dinner guests found the blueberries much too sour.'