Answer: Based on the information provided, the most accurate statement about the post-World War I population in Kansas is: "On average, fewer people lived in urban areas in Kansas compared to the rest of the country."
The statement "On average, more people worked in manufacturing in Kansas than in other parts of the country" is not supported by the information provided.
The statement "The number of immigrants moving to the state declined drastically" is not specifically mentioned in the information provided and cannot be confirmed.
The statement "The number of African Americans moving out of the state increased rapidly" is not mentioned in the information provided and cannot be confirmed.