Explanation:

- Physical Capital: This is the correct answer. Physical capital includes tangible assets like machinery, buildings, and tools. These can be bought and sold in the market.

- Human Capital: Refers to the skills, knowledge, and experience possessed by an individual or population. It is intangible and cannot be sold like physical assets.

- Service: Represents activities or benefits provided in exchange for payment. Services are intangible and cannot be sold in the same manner as physical goods.

- None of these: This option would be incorrect because physical capital can indeed be sold in the market.