Why is relative phase important?

Question: Why is relative phase important in quantum computing? A) It changes the number of qubits in the circuit B) It can affect interference in later operations C) It always changes measurement probabilities immediately D) It prevents gates from being reversible Correct: B Explanation: Relative phase may not always be visible from a direct measurement, but it can strongly affect later gates through quantum interference. Many quantum algorithms rely on controlling phase so that correct answers are amplified and incorrect paths cancel out. Topic: quantum computing / phase / interference