Answer:
A. 300 times
Step-by-step explanation:
Leeuwenhoek is best known for working on the development and improvement of microscopes and for his contribution to the development of microbiology.
It is assumed that Leeuwenhoek's microscopes have magnifying powers in the range of 50 to, at the most, 300 times, but it is not completely known as his methods of microscopy remained something of a mystery.