Amedical researcher prepares a number of doses of saline solution placebos. this is a mixture of mineral salts and water that is absolutely safe to administer and has no medical effects whatsoever. the likely purpose of these placebo doses is: . a. for use as treatments in a double blind experiment. b. for testing as a cure for dehydration. c. for a test of the hawthorne effect. d. for use on a control group in an experiment. e. for use as placebos.