Question

which type of microscope was the first to be used for studying single - celled organisms?
simple microscope
tunneling microscope
compound light microscope
electron microscope

Explanation:

Anton van Leeuwenhoek used simple microscopes to observe single - celled organisms like bacteria and protozoa in the 17th century. Simple microscopes were the earliest type among the options. Tunneling microscopes, compound light microscopes, and electron microscopes were developed much later.

Answer:

simple microscope