What is the chemicals called that are sometimes used to make the specimen visible in a microscope?

Chemicals used in making specimen visible in a microscope are called stains. They are chemical substances that enables to apply and make bacteria absorb chemicals into making them visible by having them applied with various color depending on the chemical that is applied. It makes the visible and make their structures and physical form to be seen under the use of a microscope.

Ithink your answer will be c let me know if it’s right