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.