If the Radius of a Potassium Atom Is 2

If the radius of a potassium atom is 2.27 x 10-7 mm,what is the radius in µm?

A) 2.27 x 10-16 µm
B) 2.27 x 10-10 µm
C) 2.27 x 10-4 µm
D) 2.27 x 105 µm
E) none of the above