Question

Which line from President Reagan’s Address at Moscow State University is a fact?

Democracy is the standard by which governments are measured.
Throughout the world, free markets are the model for growth.
The key is freedom—freedom of thought, freedom of information, freedom of communication.
Every four years the American people choose a new president, and 1988 is one of those years.

Answer 1

The fourth line is a fact. "Every four years the American people choose a new president, and 1988 is one of those years."

Why: U.S. presidential elections are held every four years and 1988 was an election year. (Minor clarification: saying "choose a new president" can be misleading because sometimes the incumbent is re-elected; more precisely, Americans vote for president every four years, and 1988 was one of those election years.) The other three lines express opinions or value judgments, not verifiable facts.