Aresearcher is conducting a written survey about people's attitudes toward walking as an exercise option at the local shopping mall that supports a walking program. the survey is anonymous (without codes, names, or other information) and subjects may complete the survey and place it in a box at the shopping mall exits. which of the following is the most important issue that the researcher addressed in planning the research? a. possibility of emotional distress from answering the questions themselvesb. recruitment of subjects to ensure varied characteristics of the sample sizec. confidentiality of the individual subject’s responsesd. data analysis from a large sample size