Why are multiple trials necessary in scientific investigations?
a.
multiple trials reduce the impact of random measurement errors on the overall results.
b.
multiple trials allow scientists to manipulate multiple variables at the same time.
c.
multiple trials eliminate the need for other scientists to independently verify the results.
d.
multiple trials guarantee that a hypothesis will be proven and converted into a law.

Option A, Multiple trials reduce the impact of random measurement errors on the overall results.

Explanation:

Multiple trial in an investigation is done to assure that the reading or value or observation obtained at the first trial is consistent through out the multiple trial. If multiple trials after the first trial do not produce accurate result then first trial's result is nullified. However, if the result are consistent with maximum accuracy or with little error then its impact on overall result is reduced or distributed accordingly.

Thus, option A is correct

a and c are the answeres

that is wrong, its not thymus.