When you perform research for your project, the sources you absolutely must review are
a. primary sources only.
b. primary and secondary sources.
c. primary, secondary, and tertiary sources.
d. any two types of sources as long as you have two.

c. primary, secondary, and tertiary sources.

In performing research for a project, it is necessary to consult the three types of information sources, the primary, the secondary and the tertiary sources. The primary sources refers to first hand information or the original one, that has not gone in review. Secondary sources are those information sources that has been analyzed and interpreted such as textbooks. The tertiary sources on the other hand, are the combination of both primary and secondary sources of information such as encyclopedias, almanacs, atlases and others.