Gerardo's research question for an informational paper is: How have US zoos changed in the last 20 years?

Which source would be least helpful in Gerardo's research?

A. "The Future of Zoos: Challenges Force Zoos to Change in Big Ways," an article in Time Magazine
B. "Zoos and Conservation: Policy Making and Organizational Challenges," a research paper by university scientists
C. "20 Changes: 25 Years at the Lincoln Park Zoo," a section on the Chicago zoo's website
D. Encyclopedia of the World's Zoos, a book from the local library