Answer:
The factor of shifting from an agricultural economy to an industrial economy.
Explanation:
- After the advent of industrialization, most people preferred moving to industrial towns leaving agriculture behind.
- As more people opted to work in industries, the demand for labor automatically subsided and the industry owners started exploiting their workers.
- To protect their own interests, the workers found it necessary to form unions. The membership of such unions gained for workers protection against exploitation by the industrialists.