What would increase the resistance of a copper wire?

A. decreasing the wire's thickness

B. decreasing the wire's temperature

C. decreasing the wire's length

R = ρl/A

From the equation above R = Resistance, l = length, A = Cross Sectional Area of wire.

From the equation, it can be seen that R would increase if the wire's area is reduced.

If the area of the wire is reduced, means the same thing as:

A. decreasing the wire’s thickness