Phrenology is best described as what type of theory?

Phrenology is best described as a theory indicating that the shape and bumps on a person's skull can reveal their mental traits and character. This pseudoscientific approach emerged in the early 19th century, largely credited to Franz Joseph Gall, who proposed that different areas of the brain corresponded to different personality traits and intellectual abilities. According to phrenology, by examining the surface of the skull, one could assess a person's mental faculties and even predict their behaviors.

The other options do not accurately capture the essence of what phrenology entails. While psychological assessments can involve various methods, phrenology is not considered a valid or empirical method of psychological assessment today. The theory does not specifically address animal behavior nor is it related to advances in medical understanding of the brain, making these choices less relevant to the definition of phrenology.