Answer:
(C) Conduct more repeated trials to see if the difference in time really is significant.
Step-by-step explanation:
In scientific experiments, a researcher should always take at least three measurements (ideally 5-6) to compare better and get a precise average. Two measurements are not sufficient.
Since the difference in these two measurements is 2.04 -2.00 = 0.04 only, it is incorrect to say that less or more massive objects take more time to swing. Hence, (A) and (D) options are wrong.
Not (B) because research is a process where hypothesis -> experiments -> observations -> conclusions. Hypothesis being proved wrong is still an experiment (even a successful one!) and correct conclusions are still possible.