Chapter 18 - Basic Electric Circuits - Learning Path Questions and Exercises - Multiple Choice Questions - Page 650: 7

C

The current in C must equal the sum of the currents in A and B, because the addition of currents in a parallel circuit equals the current of the equivalent resistor. We know that that should equal the current through C, as the current is constant in a series circuit. Thus $$I_A + I_B = I_C$$