What does a CNOT gate do?

Question: In a CNOT gate, when does the target qubit flip? A) When the control qubit is |0⟩ B) When the control qubit is |1⟩ C) Every time the gate is applied D) Only after measurement Correct: B Explanation: The CNOT gate has two qubits: a control and a target. If the control qubit is |1⟩, the target qubit is flipped. If the control qubit is |0⟩, the target remains unchanged. Topic: quantum computing / two-qubit gates / CNOT