Concept:The suitability of a fluid as a lubricant depends on its internal friction or resistance to flow.
Explanation:This property is called viscosity.
A good lubricant must have enough viscosity to keep moving surfaces apart.
If the viscosity is too low, the lubricant film breaks and surfaces touch.
If the viscosity is too high, it resists motion and wastes energy.
Thus, the fluid property used to judge a lubricant is viscosity.
Answer:B. viscosity (listed in the options as viscocity)