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

Secondary sources interpret and analyze primary or other secondary sources.  Option B is correct.

Generally, secondary sources are those sources which describe or comment regarding a topic which was previously presented and mentioned in another source. In other words, secondary sources comment on primary sources, which are the original source of information.

Other choices provided above, describes primary sources.

- "there are several movements that doris lessing was associated with. first of all, communism. she pursued her communist beliefs and included them in her writing, and was also a member of several communist book clubs. she is also strongly associated with feminism, her fight for equality and women's rights.

doris lessing is the kind of writer who has followers, not just readers. they have been engaged to her chiefly because of her involvement in major problems, such as politics and woman-ism."