Answer:
Out of the options given
option (a) preventing fires
is not a function of hydraulic fluid.
Explanation:
Hydraulic fluid is the medium for energy tranfer in all hydraulic sytems. Simple functioning of hydraulic fluid can be easily gained by using a fluid that does not trap gasses easily.
To transmit energy is the basic and the core function of any hydraulic fluid. Apart from this function, there are four other basic functions:
1) to transfer heat
2) to remove contaminant
3) to provide sealing
4) for lubrication