[单选题]
The graph below shows the grapang u0(owaauc4 9mo3 qd3/o)qh of j, mzk2dxr,+og 9yg/ dthe maximum kinetic energy ($E_k$)of the emitted electrons against incident frequency ($f$) plotted by a student investigating the work function for a particular metal.
Which of the following can be used by the student to get an approximate value for the work function of the metal in question?
A. Intercept X
B. Intercept W
C. Gradient at Y
D. $\frac{Speed of Light }{Intercept W}$
