Who was known for documenting the effects of the Great Depression through photography?

Dorothea Lange is renowned for her powerful photography that captured the dire impacts of the Great Depression. Her work is most famously associated with her series of photographs titled "Migrant Mother," which became iconic representations of the struggles faced by families during this difficult era. Lange's ability to convey emotion and tell a story through her images helped raise awareness of the plight of impoverished communities, influencing public opinion and policy regarding economic relief measures.

While John Steinbeck is well-known for his literature that depicted the hardships of the Great Depression, such as in his novel "The Grapes of Wrath," he utilized written words rather than visual art. Thomas Edison is not connected to this social context, primarily known for his inventions in the late 19th and early 20th centuries. Sam Brannan was a prominent figure during the California Gold Rush and did not focus on documenting the Great Depression. Thus, Lange stands out distinctly as the correct answer for her photographic contributions during that period.