Pick up the correct statements of the following.    a)    Threshold frequency does not depends on intensity of incident light.    b)    Threshold frequency is different for different metals.    c)    The intercept on X-axis of a graph drawn between stopping potential on Y-axis and frequency on X-axis gives threshold frequency.

When radiation is incident on a metal, PEE is possible only when the frequency of incident radiation is equal to the threshold frequency of the metal. Each metal has its own threshold frequency. The graph between stopping potential and incident frequency is straight line with intercept on the frequency axis. this intercept is the threshold frequency.