After conducting several experiments, the scientists presented their data to the committee, which raised some significant questions.
Correct: D
In the original sentence, the pronoun 'which' could ambiguously refer to either 'the committee' or 'their data.' To clarify that the *data* raised the questions, option D places the 'which' clause immediately after 'data,' directly modifying it. This clarifies the antecedent of 'which' without altering the intended meaning of the original sentence, a common ACT rhetorical strategy.