Final answer:
The correct answer is d) Twin study, which is a type of study used in the area of behavioral genetics to understand the role of genetics and environment in shaping human behaviors and traits.
Step-by-step explanation:
The type of study included in the area of behavioral genetics that compares the likelihood that a given behavioral trait is shared among identical and fraternal twins is known as a twin study. Behavioral genetics is the field that focuses on genes and their expression, and often employs twin and adoption studies to research questions of interest. It is important for understanding the interaction of genes and the environment in shaping behaviors and traits.
When studying human behavior, behavioral geneticists may use twin studies to compare identical and fraternal twins in order to gain insights into the relative importance of genetic and environmental factors in the expression of traits. Other methods such as longitudinal studies, case-control studies, and genome-wide association studies may be used for researching various diseases and understanding risk factors or the genetic basis of traits.