King makes allusions to multiple other texts in the course of his “I Have a Dream” speech.

Two texts that Martin Luther King uses in his speech are the Emancipation Proclamation, and the Declaration of Independence. The use of these two texts is very effective, because it reminds the people listening to the speech that freedom and equality are an essential part of the cultural fabric of America. Citing the Emancipation Proclamation is an effective way to begin the speech, because it was the document that freed African-Americans from slavery. Using this, King is able to explain to others, that despite being free for many years, African-Americans are still not being treated fairly at the time of this speech, a century later. 

Referencing the Declaration of Independence serves the purpose of promoting King's message of both freedom and equality. The Declaration of Independence was written so that the America could be free from Great Britain, and it discusses how all people are equal. King sees that there are still major issues in the United States with freedom and equality, in regards to African-Americans, so he reminds his audience of the message of America's founding, and explains how it is still relevant when giving his speech. 

Ultimately, King understands that the people listening to his speech likely respect the founding fathers of their nations, and support their legacy, so he uses allusions to these documents to show that they need to stay true to what they say they believe.

Explanation:

c. explains words’ origins and variations.

i think it could possibly be b