Citizens are required to be A: born in the United States
B: involved in the military
C: loyal to the federal government
D: members of a charitable organization

I think C, but maybe none of the above. (Depending on the strict definition of "Loyal".  You have to follow Federal laws though so I think it is C.

Explanation:

You do not need to be born in the USA to be a citizen, you can become a naturalized citizen through a legal immigration process, or marriage, or if your parents are both citizens you are automatically a citizen when you are born.

You do not need to be involved in the military to be a citizen.

You can't be against the federal government, or commit treason so I think it is C.

Being a member of a charitable organization is optional and not required for citizenship,

john smith was the first englishman to sail around the world. francis bacon served as attorney general and lord chancellor of england. he took up aristotelian ideas, arguing for an empirical, inductive approach, known as the scientific method, which is the foundation of modern scientific inquiry.