Which of the following relationships must be true according to the laws of series and parallel connections? (Select only relationships that must be true according to the laws of series and parallel connections, not those that are true in this problem only because of the particular resistances given.)

a. I_1 = I_3
b. I_3 = I_4
c. I_2 = I_1 + I_3
d. I_1 = I_3 + I_2
e. V_1= V_2
f. V_3 = V_4
g. V_1 = V_3 + V_4
h. V_2 = V_3 + V _4
i. V_1 = V_2 + V_3 + V_4