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.

Specimens are placed in a vacuum.

Explanation:

A transmission electron microscope, commonly known as TEM is one of the types of microscope that uses electrons to view the structure of cells or tissues. Since TEM uses electrons to form images, specimens must be placed in a vacuum in order for the electrons to reach and capture the specimen. Without the vacuum, electrons may be diverted by air particles before landing on the specimen.

Due to the fact that specimens to be viewed using TEM must be placed in a vacuum, only dead specimens can be viewed. Living cells cannot survive in a vacuum as the vacuum causes the fluid in them to evaporate i.e. they dry up. Hence, placing a specimen in a vacuum best explains why dead specimens must be used for the Transmission electron microscope.