The correct answer to this open question is the following.
Although you forgot to attach the options for this question we can comment on the following.
According to the information in the excerpt, Silvu’s citizenship status is the following: "Not a U.S. citizen."
Silvu was living in Romania. The text does not specify if Silvu was born in Romania. It says that Silvu has recently moved to the United States from Romania to attend college. His mother voluntarily renounced her U.S. Citizenship to become a citizen of Romania before Silvu was born and his father is a Romanian citizen.
That is why she enters the United States with permission to be a student.
If people were not born in the United States, they can get citizenship by naturalization. There are some requirements to become a citizen of the United States such as having your Green Card for at least five years, be 18 years old or more, be a person of good moral character, and be able to read, write, and speak English. If you become a US citizen, you must swear allegiance to the U.S. government.