A certain metal when irradiated by light (r=3.2×10¹⁶Hz) emits photo electrons with twice kinetic energy as did photo electrons when the same metal is irradiated by light (r=2.0×10¹⁶Hz). The v0 of metal is: A. 1.2×10¹⁴Hz B. 8×10¹⁵Hz C. 1.2×10¹⁶Hz D. 4×10¹²Hz