Final answer:
The key variables that contributed to the increase in widespread exposure and popularity of African-American music across racial, ethnic, and national boundaries beginning in the 1980s were the presence of African-American artists in mainstream media, the emergence and spread of hip-hop or rap music, and the blurring of racial lines through rock and roll.
Step-by-step explanation:
The key variables that contributed to the increase in widespread exposure and popularity of African-American music across racial, ethnic, and national boundaries beginning in the 1980s were the presence of African-American artists in mainstream media, the emergence and spread of hip-hop or rap music, and the blurring of racial lines through rock and roll. In the 1980s, African-American artists like Bryant Gumbel, Vanessa Williams, and Oprah Winfrey gained prominence on mainstream television, increasing admiration and exposure to African-American culture. Hip-hop or rap music, which originated from self-taught street musicians and addressed the experiences of inner-city life, appealed to many outside of the ghettos, contributing to the popularity of African-American music. Additionally, rock and roll played a significant role in blurring racial lines and promoting social interactions between black and white teenagers in the 1950s, spreading African-American music to a broader audience.