A Wire of Resistivity ρ Must Be Replaced in a Circuit

Multiple Choice

A wire of resistivity ρ must be replaced in a circuit by a wire four times as long. If, however, the total resistance is to remain as before, the diameter of the new wire must

A) remain unchanged.
B) be two times smaller.
C) be four times smaller.
D) be two times larger.
E) be four times larger.