Horatio wants to use part of martin luther king, jr.'s "i have a dream" speech in one of his essays. this source is best described as a/an a. secondary source. b. statistical source. c. primary source. d. annotated source.

The source Horation wants to use is best described as a PRIMARY SOURCE.

Below, I included the definitions of the 4 sources, so as to have a clearer idea.

A. secondary source: it is one that was created later by someone who did not experience in the events or participate in the conditions you’re researching. They generally are scholarly books, articles and  encyclopedias.

B. statistical source: refers to an organisation or an individual, , that is involved in the distribution of statistical data.

C. primary source. primary sources of information are those that have experienced the accounts of the events, practices, or conditions you are researching. Eg.: autobiographies, memoirs, and oral histories. Primary sources are what remain from the past, they are really the only way the current generation can hope to understand what happened before.

D. annotated source. It is a list of citations to books, articles, and documents. Each citation is followed by a brief (usually about 150 words) descriptive and evaluative paragraph, the annotation. The purpose of the annotation is to inform the reader of the relevance, accuracy, and quality of the sources cited