Final answer:
The passage about Mrs. Bertha Flowers in 'I Know Why the Caged Bird Sings' aims to inform the reader of her esteemed social position in Black Stamps, as inferred from her dignified bearing and the comparison to the town's wealthiest white woman. The correct answer is option 3.
Step-by-step explanation:
The author's purpose in including the passage about Mrs. Bertha Flowers in I Know Why the Caged Bird Sings is to inform the reader of Mrs. Flowers's social position in Black Stamps. Through the detailed description of her demeanor, her attire, and her grace under various conditions of weather, the author paints a picture of a woman who possesses a respected status within the community. This is further emphasized by the comparison of her to the wealthiest white woman in town, which indicates Mrs. Flowers's importance and standing on her side of the racial divide in Black Stamps.