The correct answer is: "all money earned in the course of a year".
Income is a flow variable, which means that it can be measured over a period of time, which in this case is typically measured for a year.
Income is an economic term which is defined as the set of all remunerations earned by an individual from any factor of production (land, labor, capital) sold in the factor markets. The types of income are: rent (remuneration for land), interest (remuneration for capital) and wage (remuneration for labor).
