Answer:
C
Explanation:
an impure substance made through chemical process
A gauge records the pressure over atmospheric pressure (0kpa on the gauge is actually the atmospheric pressure and a reading of 276kpa is 276kpa over atmospheric pressure). That means that means that to find absolute pressure you just add atmospheric pressure (around 1atm (101kpa)) to 286kpa to get 387kpa. I hope this helps.
I believe the awnser is salt water i took a test on it recently and that was the awnser.