Final answer:
Phase-contrast microscopy (option C) is the light microscope technique that is good for small, unstained specimens like single living cells or cell monolayers and makes highly transparent objects more visible.
Step-by-step explanation:
The light microscope technique that is good for small, unstained specimens like single living cells or cell monolayers and makes highly transparent objects more visible is phase-contrast microscopy. This technique takes advantage of the differences in refractive index between the components of the specimen to create contrast and enhance visibility. It allows for the observation of live, unfixed, and unstained specimens.
In phase-contrast microscopy, a phase plate is used to convert differences in refractive index into differences in intensity, resulting in a highly contrasted image. This makes it easier to see the structures within the cells and observe their movement or changes over time.
For example, in a cell monolayer, phase-contrast microscopy can reveal individual cells and their internal structures, such as the nucleus, cytoplasm, and organelles. It can also be used to study the behavior of single living cells, such as their division or migration.