A speck of dust is 1.2 x 10-6 m wide. Which of the following is the best way
to rewrite this quantity, using more appropriate units?
A. 1.2 x 10-4 cm
B. 1.2 x 10-9 km
C. 1.2 x 10-3 mm
D. 1.2 x 10-6 m