B. Laws for safer working conditions are instituted.
Explanation:
This is the statement that best represents the main topic of the outline. Option B is the statement that best shows this topic because it talks about how the laws were changed in order to institute safer working conditions. Option A talks about the way several groups motivated the change. Option C about how the fire changed everything, and option D how state legislation changed due to demonstrations. Option B is the only one that contains all methods that were used to institute change.
