Final answer:
The headings in the passage help to develop the author's ideas by presenting sections that explain how the March affected progress in the areas of voting rights, job opportunities, and desegregation.
Step-by-step explanation:
The headings in the passage (option A) help to develop the author's ideas by presenting sections that explain how the March affected progress in the areas of voting rights, job opportunities, and desegregation. These headings provide a clear structure to the passage and allow the reader to easily understand the main points being discussed. By organizing the passage in this way, the author can effectively convey the impact and significance of the March on various aspects of society.