Concept:Population is grouped by the economic activities people perform, which is known as occupational distribution.
Explanation:Occupational distribution refers to the way the labour force is divided among different jobs and economic activities.
It shows the number or proportion of people working as farmers, teachers, traders, factory workers, and so on.
The question asks for the grouping based on economic activities people engage in.
This exactly matches the idea of occupational distribution.
Answer:D. occupational distribution