Final answer:
C.Thomas Jefferson. Thomas Jefferson was the author of the document excerpt written on July 4, 1776, known as the Declaration of Independence.
Step-by-step explanation:
The author of the document excerpt written on July 4, 1776, is Thomas Jefferson. He was one of the members of the Committee of Five (which also included John Adams, Benjamin Franklin, Robert Sherman, and Robert R. Livingston) tasked with drafting the Declaration of Independence. The document was adopted by the Continental Congress on July 4, 1776, and it proclaimed the colonies' separation from Britain, laying out the reasons for rebellion and asserting the principles of liberty and equality.