A diode is considered forward-biased when its p-side (anode) is connected to a higher electric potential than its n-side (cathode), meaning $V_p > V_n$. Because the specific circuit diagrams for the options are not provided in the text, it is impossible to independently verify which option satisfies this condition. However, in the correct diagram (Option 4), the potential at the p-side would be mathematically greater than the potential at the n-side.