Why would a researcher use primary source instead of a secondary source when analyzing a historical event?

Which of the following describes a difference between an essay's body paragraph and its conclusion? o a. body paragraphs first introduce evidence, while a conclusion simply reminds readers of evidence. b. body paragraphs act as hooks for the reader, while the conclusion simply restates the essay's claim. c. body paragraphs can be any length, while the conclusion has a set number of sentences. d. body paragraphs restate the essay's claim, while the conclusion proposes claims for future essays.