Giving reasons categorize the following into stock and flow:
(i) Capital
(ii) Saving
(iii) Gross domestic product
(iv) Wealth

A stock variable is measured at one specific time, and represents a quantity existing at that point in time which may have accumulated in the past. Whereas any variable whose magnitude is measured over a period of time is called a flow variable.
(i) Capital- Capital is a stock variable as it is measured at a particular point of time.
(ii) Saving- Saving is a flow variable as it is measured over a period of time. If it was savings, which is measured at one specific time, then it would have been considered as stock variable.
(iii) Gross Domestic Product: Gross Domestic Product is a flow variable as it is measured over a period of time.
(iv) Wealth: Wealth is a stock variable. Because, wealth is the abundance of valuable resources or valuable material possessions from the past and is measured at a particular point of time.