Name two national U.S. holidays.

The correct answer includes Christmas and Thanksgiving, both of which are recognized as national U.S. holidays. Christmas, celebrated on December 25, is a significant holiday in the United States characterized by various traditions, including gift-giving and family gatherings. Thanksgiving, observed on the fourth Thursday of November, is a holiday centered around giving thanks for the harvest and blessings of the past year, commonly celebrated with a meal shared with family and friends.

The other options include days that are not considered federal holidays. For example, Labor Day is indeed a national holiday, but Valentine's Day is not recognized as such. Mother's Day is celebrated but is not a federal holiday either. Halloween, while celebrated widely, is not a national holiday and is more of a cultural observance. Thus, the pairing of Christmas and Thanksgiving remains the most accurate representation of recognized national holidays in the U.S.