Identify the flow variable from the following:

Annual Expenditure of a school.

The correct answer is Option (1) → Annual Expenditure of a school.

A flow variable is a quantity measured over a specific period of time. The term "annual" indicates a period of one year, making the expenditure a flow variable.

The other options are stock variables, as they are measured at a specific point in time:

• Distance between Punjab and Haryana is a static measure.

• Bank balance is a value at a specific moment in time.

• Investment in this context refers to the value of a portfolio at a specific moment in time.