In the context of economics, factors of production typically include land, labor, capital, and entrepreneurship. The following items you provided can be categorized as factors of production:
- The chemistry laboratories at Stellenbosch University (capital)
- A skilled bricklayer (labor)
- An unskilled laborer (labor)
- A sugar-cane plantation in northern KwaZulu-Natal (land)
However, the wages earned by a skilled bricklayer do not constitute a factor of production. Instead, wages are a form of income earned by labor as a return for their services.
Therefore, the correct answer is:
The wages earned by a skilled bricklayer.