The correct answer is option 1: Cytology. Cytology is the branch of biology that focuses on the study of cells. It involves the examination of the structure, function, and properties of cells, as well as their interactions with other cells and their environment. Cytologists study various aspects of cells, including cell division, cell signaling, metabolism, and cellular organization. They use specialized techniques and tools, such as microscopes, to observe and analyze cells at a microscopic level. By studying cells, cytologists gain insights into the fundamental processes that govern life and contribute to other biological fields, such as genetics, molecular biology, and developmental biology.

Option 2, Histology, is the branch of biology that deals with the study of tissues, rather than individual cells. Histologists study the structure, organization, and function of different types of tissues in organisms.

Option 3, Psychology, is the scientific study of the human mind and behavior, and is not directly related to the study of cells.

Option 4, Physiology, is the branch of biology that focuses on the functions and processes of living organisms, including cells, tissues, and organs. While cells are a part of physiological studies, cytology specifically focuses on the study of cells, whereas physiology encompasses a