The correct option is D Both A and B
Open heart surgery is any type of surgery where the chest is cut open and surgery is performed on the muscles, valves or arteries of the heart.
During this surgery, the heart is exposed and the patient's blood is made to bypass it. The patient needs the function of heart and lungs provided by an artificial method, and so an oxygenator is required for the circulation of oxygen.
Thus, the correct answer is option (D).