The photomicrograph displays cells taken from a human blood smear. Which calculation correctly determines the actual diameter of the neutrophil visible in the photomicrograph in micrometres ($\mu\text{m}$)?
- A$\frac{\text{length of line PQ in mm} \times 1000}{\text{magnification of photomicrograph}}$
- B$\frac{\text{length of line PQ in mm} \times 10000}{\text{magnification of photomicrograph}}$
- C$\frac{\text{magnification of photomicrograph}}{\text{length of line PQ in mm} \times 1000}$
- D$\frac{\text{magnification of photomicrograph}}{\text{length of line PQ in mm} \times 10000}$