Final answer:
The legal as well as an ethical obligation of American citizens is serving in the military if drafted.
Step-by-step explanation:
The correct answer is C. Serving in the military if drafted.
Serving in the military if drafted is both a legal and ethical obligation of American citizens. The Selective Service System requires all male U.S. citizens and male immigrants between the ages of 18 and 26 to register for potential military service. If a draft is enacted, those who are selected must fulfill their duty to serve.
While attending public school, joining a political party, and running for public office may be important civic responsibilities, they are not legally required obligations for all American citizens.
Learn more about Duties of American citizens