Size of specimens — practice question

In a photomicrograph, the length of a mitochondrion measures $15\,\text{mm}$. Its real length is $3\,\mu\text{m}$. Determine the magnification of the photomicrograph.

• A$\times 5$
• B$\times 45$
• C$\times 5000$
• D$\times 45\,000$