Analogy-based test:
A useful test for stock versus flow is the "photograph versus movie" analogy: a stock is something you could measure by taking a snapshot at one instant, while a flow can only be measured over a stretch of time. Applying this test - Labour is measured in hours worked over a period, so it is a flow. Working Capital is capital in active use, replenished and consumed continuously, so it too is measured over a period, making it a flow. Entrepreneurship is valued through managerial effort exerted over time, again a flow.
Land, by contrast, can be measured by area at a single point in time regardless of whether it is being used that instant, which is exactly the "snapshot" test for a stock resource - confirming option (4).