The excerpt from "Roll of Thunder, Hear My Cry" highlights the theme of racial injustice and its impact on the characters, particularly the children. The dialogue reflects a hierarchy influenced by race, where the character Cassie feels the need to consider the repercussions of her actions due to the societal expectations and dangers imposed by an unjust system.
The best interpretation of what the excerpt shows about the historical time period of the story is: It shows that racial injustice made it dangerous for African Americans to stick up for themselves. This is evident in Cassie's reaction to the threat of Mr. Simms's violence, indicating a reality where standing up against racial injustice could lead to physical punishment or other severe consequences.