Which subfield of psychology includes both psychological factors and physical diseases?

Health psychology

Explanation:

Health psychology can be described as a brand of psychology which is concerned with how psychological or behavioural factors influence the physical health and illness in a person. Health psychology focuses on the biological, psychological, behavioural and social factors which contribute to the health or illness of a person. This field focuses on promoting health along with the treatment and prevention of diseases. This field also tends to focus on how a person reacts to illness.