Question: Which of the following are benefits of quitting smoking? Need Assignment Help? Group of answer choices Within 12 hours, the carbon monoxide level in your blood drops to normal. Within 1-9 months, coughing and shortness of breath decrease. Within 2-12 weeks, your circulation improves and your lung function increases. Within 1 year, your risk of coronary heart disease is about half that of a smoker's. Within 20 minutes, your heart rate and blood pressure drop.