The following statements about qualitative studies of pilot projects or theory testing are correct, EXCEPT: a. If no explicit criteria are used to select a sample, it is not purposive but simply a sample of convenience. b. Informed consent is not necessary for qualitative studies of entire populations. c. Even if true identities of the study participants are disguised, the sample or population should still be described in enough detail. d. There is no clear standard of adequate sample size for a qualitative study