Nichrome Wire,often Used for Heating Elements,has Resistivity of 1

Multiple Choice

Nichrome wire,often used for heating elements,has resistivity of 1.0 × 10^-6 Ω • m at room temperature.What length of No.30 wire (of diameter 0.250 mm) is needed to wind a resistor that has 50 ohms at room temperature?

A) 3.66 m
B) 2.45 m
C) 0.61 m
D) 6.54 m
E) 22.4 m