Final answer:
The national U.S. holidays are Thanksgiving and Martin Luther King Jr. Day, making option c the correct answer. Specific historical events like the March on Washington contribute to the establishment of these holidays.
Step-by-step explanation:
The national U.S. holidays mentioned in the multiple-choice options are Memorial Day, New Year's Day, Thanksgiving, Martin Luther King Jr. Day, and Labor Day. Bring Your Daughter to Work Day, Groundhog Day, and Constitution Day are not federally recognized national holidays, though they are widely observed and celebrated. Therefore, the correct option listing national U.S. holidays is c. Thanksgiving, Martin Luther King Jr. Day.
During the March on Washington for Jobs and Freedom, a significant historical event, a large crowd gathered on the National Mall to listen to speakers. This illustrates the impact and recognition of historical events and figures that can give rise to commemoration through national holidays, such as Martin Luther King Jr. Day.