What type of discrimination did the NAACP primarily challenge?

The NAACP, or the National Association for the Advancement of Colored People, was primarily focused on challenging racial oppression and the systemic issues associated with the doctrine of "separate but equal." This doctrine was established by the Supreme Court's ruling in Plessy v. Ferguson in 1896, which upheld state laws requiring racial segregation in public facilities as long as the separate facilities were deemed equal.

The NAACP aimed to dismantle these discriminatory practices by advocating for civil rights and equal treatment under the law, emphasizing that segregation was inherently unequal and a violation of the 14th Amendment's guarantee of equal protection. Throughout its history, the NAACP has engaged in legal battles, public demonstrations, and grassroots organizing to raise awareness and combat racial injustice, making it a pivotal organization in the Civil Rights Movement.

The other options, while important social issues, did not form the primary focus of the NAACP's mission. Economic inequality between urban and rural areas, gender discrimination, and age discrimination were all significant, but they did not encompass the central racial injustices that the NAACP was created to address.