Answer:
The electron microscope
Explanation:
Fimbriae are very tiny appendages of about 3 to 10 nm in diameter found on the surface of most Gram-negative and some Gram-positive bacterial cells. They are mostly utilized as a structure to adhere to one another, to other organisms, or any other surfaces.
Fimbriae generally contain adhesins, a virulence factor that facilitates adhesion to surfaces and due to their tiny size, they can only be viewed using the electron microscope - the scanning electron microscope to be precise.