Importance of CNOT gates in quantum circuits

Question: Why are CNOT gates important in quantum circuits? A) They are used only for measuring qubits B) They can create entanglement when the control qubit is in superposition C) They delete unwanted qubits from memory D) They convert qubits into classical bits without measurement Correct: B Explanation: A CNOT gate flips the target qubit depending on the control qubit. If the control qubit is in superposition, applying CNOT can correlate the two qubits and create entanglement. Topic: quantum computing / two-qubit gates