A light microscope is used to view two structures separated by $200\ \text{nm}$. What is the distance between the structures when the magnification changes from $\times 40$ to $\times 400$?
- A$2\ \mu\text{m}$
- B$20\ \mu\text{m}$
- C$200\ \text{nm}$
- D$2000\ \text{nm}$