Read the passage from "Yellow Fever." About 15 percent of people who fall sick feel better for a day, but then the disease progresses to a more dangerous form. The next stage can include high fever, internal bleeding, unconsciousness, and harm to the heart, liver, and kidneys. Liver damage is like a poison, and it causes people's skin and eyes to take on a yellow color. Yellow fever gets its name from this symptom. In the end, 20 to 50 percent of people who develop the more severe type of yellow fever die.

Which BEST describes why the author includes this information in the article?

A. to convince readers to avoid places where yellow fever occurs

B. to encourage readers to educate others about yellow fever

C. to frighten readers into getting vaccinated for yellow fever

D. to help readers understand the effects of yellow fever​