Final answer:
The full form of Washington D.C. is Washington District of Columbia. The District of Columbia is a federal district which houses the U.S. capital, Washington. The district's name was chosen in honor of Christopher Columbus. So the correct answer is Option 1.
Step-by-step explanation:
The correct answer is Option 1: Washington District of Columbia. The designation of Washington D.C is a reference to the District of Columbia, which is a special federal district, not part of any U.S. state, in which the U.S. capital city of Washington is located. Its name was chosen in honor of Christopher Columbus, the Italian explorer who explored the Americas for Spain and laid the groundwork European colonization in the New World.
Learn more about Washington D.C.