<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A pharmaceutical corporation has asked you to assist in the development of a randomized controlled trial RCT to evaluate the response of renal cell carcinoma to a novel chemotherapeutic agent. Despite all of the benefits that an RCT has to offer, which of the following would make an RCT unacceptable with regard to study design?? A: Proper treatment response is very common, B: The treatment is not widespread in use, C: The treatment does not represent the best known option, D: The treatment has a known, adverse outcome, E: The treatment is expensive,  <response>: This is a question about the design of a randomized controlled trial RCT to evaluate a new chemotherapy drug for renal cell carcinoma. The question asks which factor would make an RCT unacceptable for this study. Choice A is incorrect because a high treatment response rate does not make an RCT unacceptable. Choice B is incorrect because whether the treatment is widespread or not does not affect the validity of an RCT. Choice C is incorrect because the treatment not being the best known option does not preclude doing an RCT. Choice D is the correct answer because if the treatment already has a known adverse outcome, it would be unethical to assign patients randomly to receive it in an RCT. Choice E about the treatment being expensive is incorrect because cost alone does not make an RCT unacceptable.D: The treatment has a known, adverse outcome 