For the batteries shown in fig. `R_1, R_2 and R_3` are the internal resistance of `E_1, E_2, and E_3,` respectively Then, which of the following is / are correct?
A. The equivalent internal resistance R of the system is given by `(R_1R_2R_3)//(R_1R_2 +R_2R_3+R_3R_1).`
B. If `E_3 = (E_1R_2 +E_2R_1)//(R_1+R_2),` the equivalent emf of the batteries will be equal to `E_3`
C. The equivalent emf to the battery is equal to `E = (E_1 +E_2 +E_3)//3`
D. The equivalent emf of the battery not only depends upon values of `E_1,E_2, and E_3` but also depends upon values of `R_1, R_2 and R_3.`