The pH scale ranges from 0 to 14, with 7 being neutral. A pH less than 7 indicates acidity, while a pH greater than 7 indicates basicity. Since the measured pH of the water sample is 6.0, which is below 7, the water is considered to be acidic.
Specifically, a pH of 6.0 is slightly acidic, as it is close to neutral but still on the acidic side.
Therefore, the best description of this water sample is:
a) slightly acidic