$\begin{array}{1 1} \text{(a) Viscosity helps in the selection of good lubricating oil} \\ \text{
(b) Light oils have low densities and easy flowability } \\\text{
(c) Heavy oils are used on parts moving with high speed} \\ \text{
(d) Light oils do not impose much drag on high-speed parts}
\end{array} $
