Explanation:
In this question we need to categorize the given statements in either micro or macro economics.
Micro economics deals with the economics at individual, group or company level. Macro economics deals with the economics at national or international level.
So the statements are categorized as follows:
1) A firm's decision about the size of its new Factory. Micro Economics.
2) The effects of the internet on the pricing of used cars. Macro Economics
3) The effect of a large government's budget deficit on the economy's price. Macro Economics.
4) A consumer's optimal choice when buying a flat screen TV. Micro Economics.