Senior doctors and radiologists have recently suggested that candidates for brain surgery actually achieve similar benefit by adopting a routine of yoga and radiotherapy if maintained for a three-year period. Although brain surgery is now considered a relatively routine procedure, it still puts the patient at risk of death during or immediately following the operation. Therefore, performing brain surgery should be immediately stopped.

Which of the following, if true, casts the most serious doubt on the conclusion drawn above?

Patients undergoing brain surgery can suffer from brain seizure, blood clotting, coma or other potentially life-threatening situations.

Almost all candidates for brain surgery are at a significant risk of suffering from brain seizure within six months of undergoing the operation.

Although patients who undergo brain surgery are often at risk of suffering from blood clotting during or after the operation, most patients survive the procedure.

Since the occurrence of coma or death during or immediately following the surgery is rare, the benefits of the surgery outweigh its dangers.

None of these