According to how the other half lives, what was one reason why it was
dangerous to live in buildings in city slums?
a. buildings did not have fire extinguishers.
b. buildings were well buil
c. buildings were well lit.
d. buildings were very dark.

According to How the Other Half Lives, the one reason which makes it dangerous to live in buildings in city slums D: Buildings were very dark.

Explanation:

Jacob Riis was a police reporter and a social reformer. His book version of “How the other half lives” was published and highlighted the plight of the people living in tenement apartments. Immigrants who had just come to United states for a better life lived in these tenements. The living conditions were pathetic. Buildings were overcrowded, poorly ventilated and quite dark. They did not even have proper sanitation, so pests and bugs were a common problem there.  There were children working in factories or were newsboys or garment workers.  

it proved indian land claims were unjustified.

nations must cooperate to bring about and maintain world peace.

nations must not wage wars or commit war crimes in a desire to control other nations.

i think i know which options you have but if these aren't options let me know