Setting is a crucial part of characterization and development of a character. Setting shows what social class the character might be in, living conditions, how they dress etc. and all of these traits are part of characterization.
The answer is a because generally they're from the time, making them primary sources
The Ewell family is like the poorest or lowest class of people in the story. The dad is a drunkard and their daughter is a lonely girl and her dad abuses her.
Randall explained, “Some birds fly south to warmer climates.”