Right-hand men. countable noun. Someone's right-hand man is the man who acts as their chief assistant and helps and supports them a lot in their work. Hope this helps! :)
C. Indian independence.
Indian involvement in World War I helped ensure Indian independence. the main battlefields of World War I were fought in Europe. While Indian soldiers did play their part in the battles of WWI, they still mostly gained by it through gaining their independence as a country.
The answer is D. Many people worried that immigrants would take their job, thus the decrease in wage.