A cell with electromotive force $E$ and negligible internal resistance is joined to a resistor network containing resistances $R_1$, $R_2$, $R_3$ and $R_4$, as illustrated. The circuit branches carry currents $I_1$, $I_2$ and $I_3$. Which equation is correct?
- A$I_1R_1 + I_2R_2 = I_3R_3 + I_3R_4$
- B$I_2R_2 - I_3R_4 - I_3R_3 = 0$
- C$E = I_1R_1 + I_2R_2 + I_3R_3 + I_3R_4$
- D$E = I_1R_1 + I_2R_2 - I_3R_3 - I_3R_4$