Explanation:

- Agriculture Sector

- The agriculture sector traditionally employed a large segment of the workforce, especially in developing countries.

- Despite its size, it's often associated with lower productivity compared to other sectors.

- Industrial Sector

- This sector includes manufacturing, construction, and mining.

- Industrialization can lead to a shift in workforce share from agriculture to industry.

- External Sector

- Typically refers to activities involving trade, finance, and interactions outside the national economy.

- Direct workforce employment is smaller compared to agriculture and industry.

- None of the above

- This option dismisses the given categories, suggesting a souce sector beyond listed options.

Correct Answer: Agriculture