The correct answer is D. All of the above.
Macroeconomics is the branch of economics that deals with the performance, structure, and behavior of an economy as a whole. It analyzes the economy at a high level, looking at issues such as inflation, unemployment, and economic growth.
National income is the total value of all goods and services produced in a country in a given year. It is a measure of the size of the economy and is used to track economic growth.
International trade is the exchange of goods and services between countries. It is a major factor in the global economy and affects the prices of goods and services, the level of employment, and the balance of payments.
The trade cycle is the pattern of economic fluctuations that occur over time. It includes periods of economic growth, recession, and depression.
All of these topics are important in macroeconomics. They help us to understand how the economy works and to make predictions about future economic performance.