Read this excerpt from "One Flu over the Cuckoo's Nest." The flu is caused by a family of influenza (flu) viruses. Some are more deadly than others. Over the past few years, a strain of bird flu viruses has infected a small number of people in Asia. Although the virus did not spread easily from person to person, it was deadly to those who became infected. In 1918, a similar but fast-spreading flu killed over three percent of the world’s people. About 500 million people were infected, with more than 1 in 10 dying of the disease. It was the world’s most severe epidemic.
How does the author emphasize the main idea in this text?
A. by providing evidence about the flu
B. by asking a study question about the flu
C. by requiring a conclusion to be drawn about the flu
D. by providing additional resources about the flu