Task: Explanation
Input (English): He is a legal citizen after entering the United States illegally.
(A) You can not be a legal citizen of a country if you entered that country illegally to begin with.
(B)No matter how he enters the country if he is living here is a technically a "citizen" or resident of that country still.
(C)You can't be a legal and law-biding citizen if you break the law.
Output (English): A