A student keeps the linear mass density of a string fixed and varies the tension, then plots the square of the measured wave speed v2 versus the applied tension FT. Which description best characterizes the resulting graph?
a) A curve that rises with decreasing slope, like a square-root function
b) A straight line that intersects the vertical axis above the origin
c) A straight line passing through the origin
d) A curve that opens upward like a parabola