Question

since viruses are typically 20 - 200 nm in diameter, the ______ microscope is best for viewing them.
light
electron
flourescent
polarizing
contrasting

Explanation:

Viruses are extremely small (20 - 200 nm). Light microscopes have a lower limit of resolution (around 200 - 300 nm for typical light microscopes), so they cannot clearly visualize viruses. Electron microscopes use electrons instead of light. Electrons have much shorter wavelengths than visible light, allowing electron microscopes to achieve much higher resolution (down to sub - nanometer levels in some cases). Fluorescent microscopes are used to visualize fluorescently labeled specimens but still rely on light (with the addition of fluorescence excitation) and have similar resolution limitations as regular light microscopes for non - fluorescently enhanced size - related visualization of very small objects like viruses. Polarizing microscopes are used to study birefringent materials. Contrasting is a general term for techniques to enhance image contrast (like in light microscopes using methods like phase contrast), but it doesn't address the fundamental resolution issue for viewing viruses.

Answer:

B. electron