Answer:
C- it help to show that some bacteria are just one cell.
Step-by-step explanation:
Anton Leeuwenhoek was the first scientist who observed the presence of bacteria in his tooth scratch under the microscope made by himself. At that time there was no concept of bacteria and he named those small creatures as animalcules which were later termed as bacteria.
Leeuwenhoek during 1670s sent the details of his experimentation on algae and bacteria to Royal Society of London.
It was due to his that primitive experiment that made the discovery of bacteria and make it known to other scientists. Therefore option C is the best option that demonstrates that bacteria are single celled organisms that are very minute. When we look at cell theory there is a postulate that shows that cell is the fundamental unit of function and structure of all living organisms. So, the work of Anton Leeuwenhoek holds substantial importance in the formulation of cell theory.
Hope it helps!