Which of the following is a stock variable?

Option 1 -> Income is a flow variable measured over a period of time (monthly/yearly).

Option 2 -> Capital is a stock variable measured at a specific point in time.

Option 3 -> Production of Bricks is a flow variable measured over a period of time.

Option 4 -> Capital Formation is a flow variable representing investment over time.

Hence, Option 2: Capital -> Capital is a stock variable because it is measured at a particular point in time, representing the accumulated value of assets, machinery, buildings, and equipment that exist at that moment. Stock variables are like a snapshot - they show the quantity at a specific instant. In contrast, flow variables (income, production, capital formation) are measured over a period of time and represent a rate of change. For example, we say "capital on December 31st was 1 million dollar " (point in time) versus "income during 2023 was $100,000" (over a period). -> correct