Question

complete the sentence with the word that best fits the overall meaning and tone.
electron microscopes capture large, detailed images of microorganisms, making them
______ tools for biomedical researchers.
indispensable
mandatory
compulsory

Explanation:

The word "indispensable" means absolutely necessary. Electron microscopes are very useful as they capture detailed images of microorganisms, so they are necessary tools. "Mandatory" and "compulsory" imply a requirement due to rules or obligations rather than the tool's inherent value.

Answer:

indispensable