An author studies maps and diary entries made by Columbus and his crew on their journeys of exploration. He writes a book interpreting the meaning behind these records. The book would be considered what type of data? a classified source a secondary source a primary source a synthesized source
It's definitely not a classified source: the maps are not a secret
It's also not a primary source: a primary source is a "direct" source, made by people who personally witnessed the events and not by someone who used other sources.
The correct answer is a secondary source: a source based on other sources.
It is secondary source because the author rewrites what Columbus said.