How does the quotation illustrate the new approach used by some reformers to implement social change in the late 1800s and early 1900s?

Innovations in photography helped this 19th century journalist Jacob Riis  improve life for many of his fellow immigrants.Jacob Riis also helped reform housing policy in New York City.Riis’s pioneering use of flash photography brought to light even the darkest parts of the city.Used in articles, books, and lectures, his striking compositions became powerful tools for social reform.Riis became a police reporter for The New York Tribune, covering some of the city's most crime-ridden districts, a job that would would lead to fame and a friendship with police commissioner Theodore Roosevelt, who called Riis "the best American I ever knew".

might be agreeing to participate ethically with other european nations in the slave trade

or notifying other european nations when taking possession   of african territories

d is the answer. leo should include the source.