Which of the following are stock variable(s)?

(A) Population
(B) Capital formation
(C) Number of students in a school
(D) Change in inventories

Choose the correct answer from the options given below:

(A) and (C) only

The correct answer is Option (4) → (A) and (C) only

A stock variable is a quantity measured at a specific point in time (e.g., as of December 31st). A flow variable is a quantity measured over a period of time (e.g., during the year 2024).

(A) Population – Stock variable. It is measured at a particular point of time (e.g., population on 1st January 2025).
(B) Capital formation – Flow variable. It represents addition to capital over a period of time, not at a single point.
(C) Number of students in a school – Stock variable. It is counted at a specific point of time (e.g., on the first day of a term).
(D) Change in inventories – Flow variable. It measures the change over a period of time.