Final answer:
A cover slip is the correct item that may be placed on top of a specimen when making a slide, used to flatten the specimen and provide a clear view when examining it under a microscope.
Step-by-step explanation:
When preparing a slide with a specimen for examination under a microscope, several materials can be placed on top of the specimen. These include a cover slip, which is a small, thin piece of glass or plastic that is placed over the specimen to flatten it and provide a clear view. Stains, such as Gram staining or acid-fast staining, may be used to enhance the contrast and visibility of certain features within the specimen.
A mounting medium might also be used to preserve the specimen and hold it in place. This medium is usually a viscous liquid that solidifies after the cover slip is applied. In summary, the correct item to be placed on top of the specimen when making a slide is a cover slip.