Using a stage micrometer scale, one unit of an eyepiece graticule was calculated as 0.005 mm.
The diameter of a spongy mesophyll cell was counted as 3.5 units on the eyepiece graticule.
What is the estimate of the diameter of the cell?
A 0.18 μm B 1.8 μm C 18.0 μm D 180 μm