Final answer:
The correct answer is option a. Demographics refers to the study of population characteristics and changes over time, but it does not include lifestyle. It includes factors such as the ratio of adults to children, family size, and the number of people in an area.
Step-by-step explanation:
The term demographics refers to the study of population characteristics and changes over time, such as birth rates, death rates, and life expectancies. While demographics includes various aspects of a population, it does not specifically include lifestyle.
Examples of demographic factors include the ratio of adults to children, family size, and the number of people living in an area. These factors are important in understanding how a population grows or declines over time, and they are often displayed in the form of a life table or population pyramid.