Which of the following on-line research strategies raises the most concerns regarding the ethical principle of respecting the autonomy of research subjects and the corresponding federal regulations requiring informed consent? a) a linguist copies portions of postings on a political blog to document the use of expletives, abbreviations, and the use of irony in the postings. b) a researcher posts a notice on an open on-line support group for interracial adoptees asking anyone who would be interested in being interviewed for her study to contact her. c) a researcher observes the communications in an open support group without announcing her presence. she is interested in observing how long members participate and how the membership shifts over time. d) a researcher proposes to join a moderated support group for cancer survivors posing as a survivor. she plans to insert comments to see how the members respond.