4. To become a citizen of the United States, you must A. have lived in the United States for at least six months. B. file a request form in a federal court. C. be at least 21 years old. D. pass an English and government test.

B. File a request form in a federal court for a green card.

Explanation:

U.S. Citizenship through Naturalization

Becoming a citizen through naturalization is a process in which a non-U.S. citizen voluntarily becomes an American citizen. U.S. citizens:

Owe their allegiance to the United States

Are entitled to its protection  

Should exercise their rights and responsibilities as citizens

Review this visual overview (PDF, Download Adobe Reader) about the general naturalization process.

To become a U.S. citizen, you must:

Have had a Permanent Resident (Green) Card for at least five years, or for at least three years if you’re filing as the spouse of a U.S. citizen.

You must renew your Permanent Resident Card before applying for citizenship if:

Your card will expire within six months of applying, or

Your card has already expired

You can apply for naturalization before you receive your new Green Card. But, you’ll need to submit a photocopy of the receipt for your Form I-90, Application to Replace Permanent Resident Card, when you receive it.  

Meet certain eligibility requirements. To see if you’re eligible, click on the link that is most similar to your situation. Some requirements may include being:

At least 18 years old when you apply  

Able to read, write, and speak basic English

Of good moral character

Go through the 10-step naturalization process which includes:

Determining your eligibility to become an American citizen

Completing form N-400, the application for naturalization, and creating a free account to submit your form online  

Taking the U.S. Naturalization Test and having a personal interview