What is the primary focus of genetics?

The primary focus of genetics is the study of how traits are inherited and expressed. This field of science explores the mechanisms by which genes, the fundamental units of heredity, are passed from parents to offspring and how these genes influence the development and characteristics of an organism. By understanding the patterns of inheritance, genetics allows for the prediction of traits in future generations and how those traits manifest in the phenotype, or observable characteristics, of an individual.

While the study of an organism's entire genetic material, the composition of proteins, and environmental impacts on gene expression are all important fields related to biology, they do not capture the core focus of genetics. The overarching theme of genetics is centered on inheritance and expression, making option B the most accurate representation of this discipline.