Answer: For question one...B. Because cells are too small to see without a microscope. It would have been impossible because cells are hard to deal with without a microscope because they are so tiny. So, without it, he wouldn't have been able to get the answer out of his discovery.
For question two...D. The nucleus is the control center of the cell. The cell theory states that, for 1., All living things are made of cells and their product., 2. New cells are created by only old cells dividing into two, and 3. Cells are he basic units of life. Cells having a nucleus is not mentioned and will never be because, cells don't need a nucleus to keep moving or keep the cell in control.
I hope this helps you! I really do hope it does.