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.

The answer is: Specimens are placed in a vacuum.

An electronic microscope is used for visualization of biological samples, which must be prepared before visualization. Vacuum is present inside the electronic microscope. It is very important and without it, electrons will hit air particles instead of the specimen. Water, abundant in the specimens, will, thus, evaporate and the specimen will anyhow be dead.

Icant be totally sure but i would say with confidence that it is example #1 about cells.