单选题 .  ①The United States Civil Rights movement, which began in the 1950s and gained momentum in the 1960s and 1970s, owed a heavy debt to African American newspapers. ②This is not to suggest that the African American press caused the Civil Rights era. ③But its continual push from 1950s for more African American rights, using a compelling form of advocacy journalism rather than the standard objective newspaper style, allowed those who in the 1950s began pushing nationally for equality to start at a far higher level than if the African American press had not existed. ④This point has largely been missed by many Americans, who seem to believe that the Civil Rights era erupted from a standstill, like a dormant geyser. ⑤But that is not how history occurs.23.  The primary purpose of the passage is to ______