What is one main characteristic of secondary sources intended for academics and students?
a. they include interesting events and characters to entertain the audience.
b. they include drawings and maps to illustrate the work.
c. they include a bibliography and citations to credit the sources.
d. they include urls for websites and blogs to support the arguments.

The correct answer is
c. They include a bibliography and citations to credit the sources.

They don't have to have drawings and maps, that depends on the field of study. They do have urls and websites but these are used as citation references, not necessarily to help prove claims. The bibliography with citations is the key to why they are important in the academic world.