Answer: (A) Realist
Step-by-step explanation:
The realist approach is one of the type of study of the various types of international policies and the main role of this type of approach is that it motivated the national interest by the moral values or the concerns.
According to the question, the defense policy and Obama administration foreign best described about the realist approach as it mainly guided about the cost an the various types of benefits from the given approach.
Therefore, Option (A) is correct.