Three ground-breaking studies in IR around 1950s and 1960s, are considered to lead the way to FPA: Decision-Making as an Approach to the Study of International Politics by Richard C. Snyder, H. W. Bruck, and Burton Sapin in 1954, “PreTheories and Theories of Foreign Policy” by James N. Rosenau in 1964, and Man-Milieu Relationship Hypotheses in the Context of International Politics by Harold and Margaret Sprout in 1956. The correct answer is E.