The Civil Rights Movement would be considered a national impact of the Declaration of Independence within the United States. The ideals expressed in the Declaration, particularly concepts of equality and rights, significantly influenced the civil rights leaders and activists who sought to address systemic racism and achieve equality for African Americans.
The other options—Czechoslovakia (1918), the Haitian independence movement, and the French Revolution—are international movements and events that were influenced by the principles of the Declaration but do not represent a national impact within the United States itself.