Secondary sources
a. provide firsthand testimony and direct evidence
b. interpret and analyze primary or other secondary sources
c. store original reflections and correspondence
d. can only be found in personal collections and private libraries

The answer is B
(Everything else would be a primary source)

I think the best answer from the choices listed above is option B. Secondary sources are sources that are interpreted and analyzed from primary or other secondary sources. Other choices given above, describes primary sources. Hope this answers the question. Have a nice day.