一道GRE逻辑题不会

Hastings‘ contracture is a disorder of the connective tissue in one or both hands,most commonly causing loss of mobility.H痉挛是一只或者两只手组织的连接错位,经常会导致活动不便.A survey of thousands of medical-insurance claims found that over 30 percent of people who had one hand operated on for Hastings'contracture underwent surgery a second time for this disorder within three years.一项研究了上千份的医疗保险索赔单的调查发现,超过百分之三十的人有一只手进行过H痉挛的手术,并且在三年内进行过两次.Clearly,therefore,a single surgical treatment of Hastings' contracture is often ineffective at providing long-term correction of the disorder很明显的,因此,对于H痉挛,一次手术治疗不能保证其长期的错位纠正.
Which of the following,if true,most seriously weakens the argument?下列如果是真的,哪个最能削弱论点.
(A) The medical-insurance claims did not specie whether the surgery was on the patient's right or left hand.医疗保险索赔没有明确出到底是病人的左手还是右手做过手术.(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.另一份研究发现90%的病人接受过H痉挛手术在手术后1个月内手的痉挛有改善.(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.所有调查的病人,在进行手术前,保险公司都要求他们向优秀的外科医生询问建议.(E) Many people who have Hastings' contracture choose to tolerate its effects rather than undergo the risks of surgery.
答案是A,CD为何不对呢?排除它因?
个人觉得,选A是因为有可能那百分之30的人都是双手痉挛,所以第一次手术是左手,第二次是右手,再说以,结论就不能说,一次手术是不能长期有效的.
C项,1个月内有改善,但是没有说之后怎么样,有可能三年内还要继续做手术,所以不影响结论：一次手术不能长期有效.
D项,其实我觉得这完全不会影响结论啊~
可以交流一下啦,都是个人意见
真的是很难的题但是D我可以理解为病人是在手术前被保险公司要求组进行二次手术的，而并非是因为一次手术无效？D的意思是 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.调查里的那些病人，在进行手术前，保险公司都要求他们向优秀的外科医生询问建议。怎么可以理解为保险公司要求他们做二次手术呢？a second opinion在这里是补充意见的意思，不能理解为二次手术~ 关键还是对D理解的问题吧，AC懂了吗？