Which microscope did anton van leeuwenhoek use to observe single-celled organisms?
a) simple microscope
b) compound light microscope
c) electron microscope
d) tunneling microscope

the microscope that Anton van Leeuwenhoek use to observe single-celled organisms is : a. simple microscope, which is the type of microscope that only has one lens. Anton van leeuwenhoek conducted his studies in the 1600s. During that time period, we haven't developed any type of high-end microscope that exist today

Distillation.  distillation is the correct answer.