Question

Why was the microscope and its improvement an important part of the development of the cell theory?

Answer 1

This is the exact answer they're looking for:

The microscope was important in the development of the cell theory because it allowed scientists to study cells more closely. The better the microscopes became, the more details about cells were observed, which led to theories about the cell.

Answer 2

This is just from my personal knowledge so I apologize if it's incorrect or not what you're asking but: The microscope was the practically the only way to actually SEE cells. And if others tried to disprove they were cells then by improving the microscope would prove cell theory.