Which of the following is an example of a biological sub-discipline?

The correct answer is biochemistry because it is a branch of science that explores the chemical processes and substances that occur within living organisms. This field specifically focuses on the molecular mechanisms that underpin biological functions, making it a core biological sub-discipline. Biochemistry combines principles from both biology and chemistry to understand the structure and behavior of biological molecules, such as proteins, nucleic acids, carbohydrates, and lipids, which are essential for life.

On the other hand, geometry and philosophy do not pertain to the study of living organisms or biological processes. Geometry is a branch of mathematics dealing with shapes, sizes, and properties of space, while philosophy encompasses the study of fundamental questions about existence, knowledge, values, and reasoning. Astrobiology, while related to biology, focuses specifically on the potential for life in the universe outside of Earth, thus it can be considered an interdisciplinary field rather than a sub-discipline of biology itself in the same way that biochemistry is.