we need to prove that the strike for the seats happened due to the influence of external factors or other societal influencers
A. A report on the dangers of non-ergonomic seating that was televised on a national news program.
Option A proves exactly that! it was the reports that caused the strike and not the workers themselves from internal factors!
B. Many of the workers at factory X are well-read and politically active.
this is irrelevant
C. There are many factories other than factory X in which the same conveyor belts and seating are used, and there have been no strikes at these factories.
Other factories are out of scope
D. Some cases of unrest in the workplace result from worker dissatisfaction.
this is kind of a weakener option as it proved its the dissatisfaction of the workers due to internal factors rather than external factors that should have influenced the workers
E. There is no single problem with either the conveyor belt or the seating at factory X that can be said to have caused the workers to strike.
this is irrelevant... even if there is a problem or not we much prove the strikes happened due to other external factors