Answer:
Option C. Is used to cool the drill bit and to flush rock cuttings up and out of the drill hole
Step-by-step explanation:
Drill mud plays a vital role in the drilling process. Its addition into the well-bore does a lot in enhancing the drilling processes and activities.
Among other importance and function of the drill mud /fluid:
1. It is used to cool off the drill bit
2. It flushes rock cuttings out of the drill hole
3. High pressure control
4. Providing buoyancy
5. Lubrication