Answer:
The overall impact of Douglass ending the passage this way is:
A. It ties the main idea--Douglass' strong drive to learn to read--to his overarching hope for freedom.
Step-by-step explanation:
The reason behind this answer is that in this passage Douglass uses a stylistic device to link his liberty with the ability to read. To justify that the boys can read and they will be free at the age of 21. However, he is a slave for life and that he is also incapable of reading. Portraying that reading would suffice his hope of liberty.