Read the draft passage. Paragraph 1: Engineers measured vibration at several points in a building's ventilation system. Their tests identified the most likely source but did not establish that every sound had the same cause. Paragraph 2: The revision should retain the engineers' determination and its limited scope. Underlined sentence: "The determination of the engineers, after measuring several points in the system, was that a loose access panel caused the strongest vibration." Which choice best repairs the sentence's delayed or obscured subject-verb core?