What is an example of a primary source?

I’m not sure on this one.

During the 1980s, profit from the sale of weapons to iran was used to stop the communists in costa rica. start a proxy war in el salvador. support the contras in nicaragua. stage a coup d’état in guatemala.

All of the following programs were responsible for improving the quality of entertainment experienced by americans, except which? a national endowment for the arts b. the corporation for public broadcasting c. national endowment for the humanities d. department of housing and urban development

Which subsystem includes the air we breathe