Correct option is (a) 0.1- 5µm
The best explanation: The pore size on microfiltration membranes ranges from 0.1 – 5 um, and has the largest pore size of the four main membrane types. Its pores are large enough to filter out such things as bacteria, blood cells, flour, talc and many other kinds of fine dust in solution. This can be contributed to its pores which are relatively large compared to other membranes; it can be operated under low pressures and therefore low energy.