Just took the test and D: Standing Wave is the answer! :)
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:
<span>A. decreasing the wire’s thickness</span>
The answer is 0 because of the velocity “u” doesn’t A