Which branch of biology focuses on the study of cells?

Cytology is the branch of biology dedicated to the study of cells, including their structure, function, and behavior. It examines the internal components of cells, such as organelles, nucleus, and cytoplasm, and can involve a variety of techniques, including microscopy and cell culture. This field is essential for understanding the fundamental unit of life, as cells are the building blocks of all living organisms.

In contrast, genetics focuses on heredity and the variation of traits among organisms, primarily through the study of genes and DNA. Histology, while related, is the study of tissues and their organization within organs rather than individual cells. Biochemistry deals with the chemical processes and substances that occur within living organisms, including the molecular mechanisms underpinning cellular functions. While all these fields are interconnected, cytology specifically zeroes in on the cellular level, making it the correct choice for this question.