Which of the following, if true, most seriously weakens the argument? A. The medical-insurance claims did not specie whether the surgery was on the patient's right or left hand. B. The surgical techniques used to treat Hastings' contracture are identical to those used successfully to treat certain work-related injuries to the hand. C. A separate survey found that 90 percent of patients operated on for Hastings' contracture report increased hand mobility within one month after the surgery. D. All of the patients in the survey were required by their insurance companies to seek a second opinion from a qualified surgeon before undergoing the operation. E. Many people who have Hastings' contracture choose to tolerate its effects rather than undergo the risks of surgery.