Psychologists study _____.

• A. economic systems
• B. only physical health
• C. the structure of the universe
• D. behavior and mental processes

Answer: (D)

Verified step by step guidance

1. Identify the main focus of psychology as a scientific discipline, which is to understand human and animal behavior as well as mental processes.
2. Recognize that psychology does not primarily study economic systems, physical health alone, or the structure of the universe, as these belong to other fields like economics, medicine, and physics respectively.
3. Understand that behavior refers to observable actions, while mental processes include thoughts, feelings, and cognitive functions that are not directly observable.
4. Combine these concepts to see that psychology encompasses both external behaviors and internal mental activities.
5. Conclude that the correct answer is 'behavior and mental processes' because this best captures the scope of psychological study.