Your friend Bill has agreed to take part in a medical study. Bill has signed all the paperwork and wonders: If he doesn't do well, can he still withdraw from the study? Based on the book's coverage of informed consent laws, you are able to tell him:Select one:a. He may withdraw from the study at any time. b. He may withdraw only after the study is at least 30% complete. c. Both "He may withdraw only after the study is at least 30% complete," and "He may withdraw from the study if he is willing to pay an early withdrawal fee." d. He may withdraw from the study if he is willing to pay an early withdrawal fee.