What does the Aperture Priority mode setting do when you take a photo of a sunset/sunrise? And how do you under-expose in the setting?

In one to two paragraphs, explain how changing context and interpretation have influenced viewpoints of dorothea lange’s portrait "migrant mother.” in your analysis, be sure to include the photograph’s meaning amid changing social, economic, and political climates, as well as the photograph’s value to photojournalism. include supporting evidence in the form of details, statistics, facts, or quotations.