Final answer:
Atticus tells Jem that African Americans cannot sit on a jury in Alabama, reflecting the racial injustices of the time.
Step-by-step explanation:
Atticus tells Jem that African Americans cannot sit on a jury in Alabama. This is reflective of the historical context within which To Kill a Mockingbird is set, a time when segregation and racial injustice were prevalent in the American South. The legal system, including jury selection, was deeply influenced by racist attitudes and laws that predominantly affected African Americans. Cases like the Scottsboro Boys in Alabama highlighted these injustices, with all-white juries delivering guilty verdicts despite evidence to the contrary. The trials and convictions underscored systemic inequality and contributed to the burgeoning civil rights movement that sought to challenge and change these discriminatory practices.