The microscope in cell studies — practice question

The diameter of a cell organelle is $4 \times 10^{-1}\,\text{mm}$. What is the diameter in $\mu\text{m}$?

• A$4 \times 10^{1}\,\mu\text{m}$
• B$4 \times 10^{2}\,\mu\text{m}$
• C$4 \times 10^{3}\,\mu\text{m}$
• D$4 \times 10^{4}\,\mu\text{m}$