Concept:To boycott means to refuse to attend or participate in an event as a form of protest.
Explanation:The sentence says the unionists did something to the meeting with management.
If someone boycotts a meeting, they deliberately stay away from it.
This fits the context of unionists showing disagreement with management.
The other words do not fit: "rejected" means refused an idea or offer, not an event.
"Hindered" means slowed down or obstructed, which does not match the action.
"Banned" means officially prohibited, which is not what unionists would do to a meeting.
Answer:C. boycotted