Answer:
Locked doors is the correct answer.
Step-by-step explanation:
The triangle shirtwaist company factory fire in New York city killed more than 140 workers. It was one of the most infamous incidents because the death of workers could have been prevented. Neglected safety features and locked doors in the building were two causes of deaths. This incident shed light on the working conditions in factories and led to the development of many laws for the safety of workers.