A.I. Explanation:

Option 1: "to show that the desert is divided into plots of land for people to purchase."

Explanation: This option focuses solely on a specific detail about California City, which is mentioned in the text. However, it does not capture the writer's main purpose, which is to compare and contrast the two cities. The text discusses the division of land but does not emphasize this as the main point.

Option 2: "to contrast two cities, although there is also some comparison."

Explanation: The writer's main purpose is to contrast Songdo and California City, highlighting their differences in size, population, and success in meeting expectations. The text explicitly states that while both cities are created by private individuals, their outcomes are different, making this option the most accurate representation of the writer's intent.

Option 3: "to highlight that demand was underestimated."

Explanation: This option incorrectly narrows the focus to California City's demand issues. While the text mentions that demand was overestimated, it does not suggest that this is the main purpose of the writing. The overall theme is about contrasting the two cities, not just focusing on demand.

Option 4: "to show that even private individuals can have a vision of the perfect city."

Explanation: This option suggests a general idea about private individuals having visions for cities, but it does not reflect the main purpose of the text. The writer is more concerned with contrasting the outcomes of Songdo and California City rather than simply stating that private individuals can have visions.