Macroeconomics primarily deals with which of the following?

Macroeconomics is the branch of economics that focuses on the economy as a whole, analyzing large-scale economic factors and how they interrelate. One of the core aspects of macroeconomics is examining the broader economic indicators, such as national income, output, overall employment, inflation, and investments, and how these elements influence the performance of an entire economy.

The relationship between income and investments of a country is fundamental in macroeconomic analysis because it helps to understand how resources are allocated on a national level and how economic policies can influence growth and stability. For instance, higher national income can lead to increased investments, which can further stimulate economic growth. Therefore, focusing on this relationship reflects the key concerns of macroeconomics regarding how economies function and evolve over time.

In contrast, the other options pertain to microeconomic aspects, which concentrate on smaller units within the economy, such as individual businesses or consumers. These focus more on specific behaviors or sectors rather than the economy's overall performance and trends. Thus, recognizing macroeconomics as dealing with the broader relationship between national income and investments aligns correctly with its objectives and scope.