A 55-year-old man presents with chronic cough and exertional dyspnoea. He has smoked one pack per day for 35 years. Spirometry confirms moderate COPD. Which counselling message regarding smoking cessation is most consistent with Canadian guidance?ACutting down gradually is sufficient; quitting completely is unnecessaryBQuitting smoking at this stage will not improve his prognosisCComplete smoking cessation is the single most effective intervention to slow COPD progression, and pharmacotherapy plus counselling should be offeredDSwitching to cigars is saferEOnly nicotine replacement therapy without behavioural support is usefulCheck my answer