Size of specimens — practice question

In a photograph, the nucleus of a plant cell measures $2\,\text{mm}$ across. If the magnification of the cell is $\times500$, what is the actual size of the nucleus?

• A$0.00002\,\text{mm}$
• B$0.004\,\text{mm}$
• C$0.04\,\text{mm}$
• D$250\,\text{mm}$