Microeconomics is the sub-field of economics that studies the behavior and decisions of the smallest decision units such as individuals or households and firms. On the other hand, Macroeconomics is the study how a country’s economy as a whole works, and it pays special attention to the effects of various policies pursued by the government. Thus, decisions about purchasing which car (cheap or expensive) and going on a holiday (abroad or in the country) by a household, and decisions about employment and advertisement expenses by a company are the subject matters of microeconomics. On the contrary, how to control inflation is the study area of macroeconomics. The correct answer is D.