In a transmission electron microscope (TEM), magnetic lenses are used to focus the electron beam. Which of the following best describes the function of the objective lens?

• A. It produces and focuses a parallel electron beam onto the specimen surface.
• B. It generates the high potential difference that accelerates electrons from the filament.
• C. It focuses the electrons that have passed through the specimen to form the first, highly magnified intermediate image.
• D. It casts the final magnified image onto a fluorescent screen, photographic plate, or CCD detector.

In a particular TEM, the electrons are accelerated from rest through a potential difference of $18.0kV$. Relativistic effects are negligible at this accelerating voltage.

Suggest, with a calculation, whether a crystal lattice with a plane separation of $0.050nm$ can, in principle, be resolved in this TEM.