Question

which reason best explains why dead specimens must be used with transmission electron microscopes?
electrons pass over the specimen.
the lights that are used are harmful to the specimens.
specimens are placed in a vacuum.
the image that is produced is two dimensional.

Explanation:

In transmission electron microscopes, specimens are placed in a vacuum. Living specimens cannot survive in a vacuum environment. Electrons passing over the specimen is a characteristic of scanning electron microscopes. The lights are not the issue as electron microscopes use electrons, not light. The two - dimensional image is a result of the technique but not the reason for using dead specimens.

Answer:

Specimens are placed in a vacuum.