According to one acid-base theory, water can act as a base because a water molecule can 1) donate an H+ ion
2) accept an H+ ion
3) donate an H- ion
4) accept an H- ion

There is no reason to think the results are biased or not conducted properly but you should not assume the results are correct just because they were done in a laboratory so the answer would be c. it is likely to be reliable because the results support the conclusion presented.