Which option exemplifies incorrect modifier placement leading to unclear meaning?

In the provided sentence, the placement of the modifier "purring softly" creates ambiguity regarding which noun it is intended to modify. It could suggest that "the kitten" is doing the purring softly or potentially imply that the act of being beside the leg is being performed softly. This makes it unclear whether the adverb "softly" describes the kitten's purring or the manner in which it is beside the leg.

In contrast, the other options maintain clarity in their modifiers. For instance, when the sentence states that the "kitten nuzzled up against my leg, purring softly," it is clear that the kitten is nuzzling and also purring softly during that action. Similarly, the other sentences clearly indicate the action or state of the kitten without confusion about what is being modified. Thus, option D stands out due to its unclear modifier placement, leading to a lack of precise meaning.