Economic resources are classified as either stock or flow:
Stock Resource: Quantified at a specific point in time. Land exemplifies a stock resource as its existence is independent of time and it is not depleted through use like labor or capital.
Flow Resource: Measured over a period. Labor (hours worked), working capital (utilized over time), and entrepreneurship (managerial effort over a duration) are examples of flow resources.
Thus, only land constitutes a stock resource among the provided options.