Answer:
A. by providing examples of each president's accomplishments.
Step-by-step explanation:
The author supports the claim that the four presidents on Mount Rushmore "represent the most important events in the history of the United States" by providing examples of each president's accomplishments.
Their striking accomplishments actually leads to the important events in the history of U.S.
Due to the accomplishments of George Washington, he is known to represent the birth of the United States. The accomplishments of Thomas Jefferson made him represent the growth of the United States. Abraham Lincoln's accomplishments is what makes him to be represented as the presevation of the United States. Roosevelt's accomplishments makes him to be represented as the development of the United States.
The accomplishments of these presidents makes them stand out and I believe this is the reason Borglum choose them.