Imagine that your teacher has asked you to research Lewis and Clark's journey across Louisiana Territory. You need to find

secondary sources that will help you understand how this journey progressed and what was accomplished during the journey
Which of these documents is the best example of a secondary source?

A. a monograph that interprets the importance of the journey

B. a collection of drawings made by William Clark of places he saw

C. a copy of Meriwether Lewis journal he kept on the journey

D. a map created by Lewis and Clark that they used while exploring the Missouri River