Final answer:
The acronym for the chief professional organization for psychologists in the United States is a) APA, the American Psychological Association. It is the largest organization for psychologists in the world and includes a variety of divisions and specialties.
Step-by-step explanation:
The acronym for the chief professional organization for psychologists in the United States is a) APA, which stands for the American Psychological Association. This organization is significant within the field of psychology, and it is known for its mission to advance and disseminate psychological knowledge to improve the lives of people.
The APA is the largest group of psychologists in the world and includes a wide range of divisions and specialties, encompassing everything from biopsychology, which investigates how biology influences behavior, to behaviorism, which focuses on the observation and control of behavior. Moreover, the APA embraces the biopsychosocial model, acknowledging the complex interactions between biology, psychology, and social factors in determining health. The diversity of the APA is also exemplified in its commitment to ethnicity-based organizations that spark research on culture's role in psychology.