C) details of cell structures needed to be distinguished.
Explanation:
The general principal of electron microscopy is analogous to light microscopy except that it uses electrons to analyse the specimen instead of light.
Electron microscopy focuses a beam of electron on the target sample and records the difference in absorption by different surfaces.
Electron microscopy is used to get the detailed structure of cells and surface features of various viruses and bacteria.
However, it is not possible to view living biological samples through electron microscope because high velocity electron have immense energy to kill living cells.
