A21st-century expert on egyptian history writes a biography describing the life of cleopatra, an egyptian pharaoh who died in 30 bce which of the following best describes the book?
a periodical source
b chronological source
c secondary source
d primary source

The book is a secondary source. The author must have utilized the already available information about the life of Cleopatra, who died in 30BCE. By using those primary sources, as well as incorporating his own analysis, the author has created this book as a secondary source.