10. a photojournalist who documented the living conditions of the urban poor was

 t. Jacob Riis

Explanation:

Jacob (August) Riis was a journalist that documented social problems. He was born in Denmark, but was an American citizen.

Riis photographed in New York, and is famous for choosing the impoverished citizens of New York as subjects of his photography. He captured the social and economic problems of the urban population and their poor living and working conditions.

Riis photographed in the last decades of the 19th century.

i think the answer is b.