Highlight details that explain why it is important to use current information. Whenever you read nonfiction, it's a good idea to check and see what the author has to say about how he or she found out about the topic. It helps you figure out how reliable the information is. (However, even reliable work gets outdated -- especially in science, where new information and discoveries can take surprising turns.)

—A Black Hole Is NOT a Hole,
Carolyn Cinami DeCristofano

Why would it be a problem if someone used old scientific research as a source?

A. New discoveries might have replaced old research.
B. The author might not have used reliable sources.
C. Reliable research seldom changes.
D. Old scientific research cannot still be valid.