The correct answer is option 'D': Rural agrarian, demographic transition, urban industrial.

Explanation:
The demographic transition theory is a model that explains the historical shift of birth and death rates in a population. It describes the transition from a pre-industrial society with high birth and death rates to an industrialized society with low birth and death rates. This theory is divided into three stages, which are as follows:

1. Rural agrarian:
- In this stage, both birth and death rates are high, resulting in a relatively stable population size.
- The society is primarily rural and agrarian, with limited access to healthcare and education.
- High birth rates are necessary to counterbalance the high death rates caused by factors such as disease, famine, and lack of medical advancements.
- This stage is characterized by a high dependency on agriculture for sustenance and limited industrialization.

2. Demographic transition:
- The second stage is marked by improvements in healthcare, sanitation, and living conditions.
- Death rates start to decline due to advancements in medical science, access to clean water, better nutrition, and improved public health measures.
- Birth rates remain high, leading to a rapid population growth during this stage.
- The transition from the first stage to the second stage often occurs due to the introduction of healthcare systems, increased access to education, and the spread of knowledge about contraception.

3. Urban industrial:
- In this stage, birth rates gradually start to decline due to various factors, including urbanization, industrialization, and increased education and employment opportunities for women.
- The decline in birth rates is also influenced by changes in societal norms, such as smaller family sizes and the desire for a higher standard of living.
- Death rates continue to remain low, leading to a slower population growth rate.
- The society becomes more urbanized and industrialized, with a shift from agriculture to manufacturing and services as the primary sources of employment.

Overall, the three stages of the demographic transition theory, namely rural agrarian, demographic transition, and urban industrial, represent the different phases a population goes through as it transitions from a pre-industrial to an industrialized society, with changes in birth and death rates along the way.