The following graph shows the variation of photoelectric current for a photosensitive metal .

(a) Identify the variable X on the horizontal line.
(b) What does the point A on the horizontal axis represent?
(c) Draw this graph for three different values of frequencies of incident radiation `v_1, v_2 and v_3 (v_1gtv_2gtv_3)` for same intensity.
(d) Draw this graph for three different values of intensities of incident radiation `I_1,I_2,I_3 (I_1gtI_2gtI_3)` having same frequency.