The incorrect statement with regard to the study of economics is option 'D': The study of investment.

Explanation:

Introduction to Economics:
Economics is the study of how individuals, businesses, and governments make choices regarding the allocation of resources to satisfy their wants and needs. It is a social science that helps us understand the production, consumption, and distribution of goods and services.

The Study of Consumption:
- Consumption refers to the use of goods and services by individuals and households to satisfy their wants and needs.
- The study of consumption is an essential component of economics as it helps economists analyze the patterns of consumer behavior, factors influencing consumption decisions, and its impact on the overall economy.

The Study of Production:
- Production refers to the process of creating goods and services using various inputs such as labor, capital, and technology.
- The study of production in economics involves analyzing factors of production, production techniques, productivity, and the relationship between inputs and outputs.
- It helps economists understand how production decisions are made, the efficiency of production processes, and the overall productivity of an economy.

The Study of Distribution:
- Distribution refers to the allocation of goods, services, and income among individuals, households, and different sectors of the economy.
- The study of distribution in economics focuses on analyzing the factors influencing the distribution of wealth, income inequality, and the impact of various policies on the distribution of resources.
- It helps economists understand the fairness and efficiency of resource allocation and the implications for economic growth and welfare.

The Study of Investment:
- Investment refers to the expenditure on capital goods such as machinery, equipment, and infrastructure with the aim of increasing future production and generating income.
- The study of investment is a crucial aspect of economics as it helps economists analyze the determinants of investment decisions, the impact of investment on economic growth, and the relationship between saving and investment.
- It also involves analyzing investment patterns, investment policies, and their implications for the overall economy.

Conclusion:
In summary, the study of economics encompasses the analysis of consumption, production, and distribution. The incorrect statement is option 'D' because the study of investment is an integral part of economics and plays a significant role in understanding the dynamics of the economy.

Generally economics works on three factors:
production
consumption
distribution
so economic does not consider investment