Answer:
To better explain some of the ideas in the main text.
Step-by-step explanation:
Supporting text are used to give additional information as well as support the main point. They bolster the main claim or idea in a text. John DiConsiglio used supporting text in "When birds get flu," to better explain some of the ideas in the main text to help the reader understand the text better.
The text talks about the "Spanish flu" which millions of people were affected, the pandemic spread through North America, Europe,Asia,Africa, Brazil as well as the South Pacific.