In the clinical area, most of the research has centered on analyses of the disordered thinking of:

In Taiwan, prenatal exposure to high levels of __________ in rice oil resulted in low birth weight, discolored skin, and delayed cognitive development

A) dioxins B) mercury C) polychlorinated biphenyls (PCBs) D) lead

A psychologist compares groups of patients who receive social skills training to similar groups of patients who do not receive social skills training. Patients at several hospitals are studied. This research is an example of a

a) correlation. b) case study. c) clinical trial. d) cross-sectional study.