Critics of CAM argue that few double-blind, placebo-controlled trials have demonstrated effectiveness. CAM advocates argue that a. many techniques used in conventional medicine have not been evaluated by this method either. b. double-blind, placebo-controlled trials constitute a flawed method for evaluating health research. c. researchers are already biased against CAM; therefore, the research is not fair. d. the National Center for Complementary and Alternative Medicine is underfunded.