Explanation:

- Option 1: Half

- Suggests 50% of the urban workforce is in the secondary sector.

- This would indicate a major reliance on manufacturing and industry.

- Option 2: One-third

- This implies around 33% of urban workers are in the secondary sector.

- It shows a significant, but not predominant, industrial engagement.

- Correct Answer: Typically aligns with global urban workforce trends.

- Option 3: One-fourth

- Indicates about 25% involvement in the secondary sector.

- Suggests a diverse economic distribution in urban areas.

- Option 4: One-fifth

- Points to 20% of the workforce in this sector.

- Implies a stronger presence in other sectors like services.