Final answer:
The Charity Organization Society's exhibit of photographs in 1900 played a critical role in passing legislation that improved public health in New York by leading to the enactment of some of the nation's first laws concerning the improvement of tenements.
Step-by-step explanation:
The passage of new tenement laws in New York was a direct result of the efforts by reformers and photographers who exposed the dire conditions of living spaces through powerful images. These images, which were part of a broader social reform movement, played a critical role in catalyzing public and political support for legislation that aimed to improve living conditions for the working class in the city. The result was significant for public health, as healthier living spaces contributed to the reduction of diseases prevalent in tightly packed urban settings.
Considering the provided context and the historical efforts to improve urban living conditions in New York, the photographs led to an act that most closely aligns with improving public health through legislation that enforced better housing standards. Therefore, the correct answer to the question is (B) Improved public health.