A silver wire has a length of 39.0 m and a resistance of 2.60 Ω at 20.0°C. Assuming a circular cross-section, what is the wire's diameter (in mm)? The resistivity of silver at 20.0°C is 1.59x10^-8 Ω*m.

A) 0.23 mm
B) 0.45 mm
C) 0.67 mm
D) 0.91 mm