THEVENIN'S THEOREM states that any linear two-terminal network can be REPLACED by

1. THEVENIN: any linear two-terminal network is equivalent to a single voltage source $V_{TH}$ in series with a resistor $R_{TH}$. 2. $V_{TH}$ = open-circuit voltage at the terminals. 3. $R_{TH}$ = resistance seen looking back into the network with all independent sources DEACTIVATED (voltage sources → short, current sources → open). 4. Greatly simplifies analysis of complex circuits. 5. Option B is NORTON's theorem. Other options are wrong. _Source: Tony Kuphaldt, "Lessons in Electric Circuits — DC", Vol I, Ch 10 (Thevenin)._