The significant aspect of the dates on which each seminal document was written lies in the context of American history regarding civil rights and the ongoing struggle for equality.
Abraham Lincoln delivered the Gettysburg Address on November 19, 1863, during the Civil War, a time when the nation was grappling with the issues of slavery and the fight for a united country. His speech emphasized the ideals of liberty and equality that formed the foundation of the United States, suggesting that the sacrifices made in the Civil War were necessary to uphold those principles.
Martin Luther King Jr. wrote his "Letter from a Birmingham Jail" on April 16, 1963, one hundred years later, amidst the Civil Rights Movement. King’s letter was a response to criticism of his activism and aimed to highlight the persistent racial injustices faced by African Americans, questioning why, a century after Lincoln's address, the rights outlined in the Declaration of Independence were still not fully realized for Black citizens.
Thus, the centennial of Lincoln's speech served as a poignant reminder and critique of the progress (or lack thereof) towards racial equality in America, making King's letter an important continuation of the conversation initiated by Lincoln about justice and equality in the nation.
So, among the responses given, the most accurate is:
King intentionally wrote his letter one hundred years after Lincoln’s speech to draw attention to the ongoing injustices Black citizens faced.