It is important to make certain that your source for historical research is a0.

The correct answer is Primary sources are first-hand accounts of events or time periods in history

The research project is characterized as an action to be developed, necessary in turn, and which foresees everything that will be developed through the research, that is, in it the researcher reveals his main intentions, explains the focus, the direction that the it will guide, express his real interests and highlight the questions that prompted him to proceed this way or that.

i also think it is c

a is the final : )