What is a central idea that this text presents about the Middle Ages?

The correct answer is A) he presents the central idea first. DiConsiglio organizes the text in “Diseases Central” to present the central idea in that he presents the central idea first. DiConsiglio includes supporting texts in “When Birds Get Flue” to explain more deeply the ideas of the main text. The supplemental text “Disease Central” is included to explain why CDC is involved in the case of bird flu. This way the reader can understand the role of CDC in response to mortal diseases.  

i would need to know the specific part of the passage your referring to ?