I came to the U.S. at the age of 24 as an F-1, student, non-immigrant visa. Therefore I did not register for selective services. Now I am over 40 and in the process for applying for U.S. citizenship. On the N-400 U.S. citizenship form, question 33 is asking "Are you a male who lived in the United States at anytime between 18th and 26th birthdays in any status except as a lawful nonimmigrant". Do I answer "Yes" or "No". If I answer "Yes" they require a letter explaining why I did not register. Please advice.