Answer:
A. Whether it is willing to follow international laws set by the UN
Step-by-step explanation:
US charter is open to all peace loving countries who are willing to accept the UN charter and follow the obligations. A country is added to the UN by General assembly on the recommendation the security council. US is neither a state nor a government hence it doesn't have the authority to assume diplomatic relations. The membership of a new state is decided by other states and government and is directly linked to willingness to accept the diplomatic relations with other countries.