Identifying Organizational Structure in Rhetorical Analysis

Read the following excerpt from a speech advocating for literacy:

"In our modern society, literacy is not just a valuable skill; it's a necessity. Imagine a world where every individual has the power to read and write. This is not merely a dream; it is a crucial goal we must achieve. First, we must ensure that every child has access to quality education. Next, we need to foster a culture of reading within families and communities. Lastly, we should support libraries and educational programs that promote literacy. By taking these steps, we can create a more informed and engaged society."

In the excerpt, what type of organizational structure does the author primarily employ to develop their argument?