There are divergent factors which constrain rationality of leaders.

First, the way how they perceive the external reality shapes the limits of their rationality. 

One other factor that appears to curtail the degree of rationality of people is the particular group environment in which they find themselves in discussing foreign policy issues. The pressure of group thinking is a very important psychological restraint affecting the rationality of individuals.

The tendency to refer to historical analogies and apply cognitive shortcuts is another factor that appears to constrain rationality.

Leaders might also think that they, the countries they lead, represent the good whereas others the bad. This is what is called in the literature as attribution bias. If something positive happens in their foreign policy contributing to the national interests of their countries, they tend to think this is because of their good intentions and benevolent policies. If something negative happens in the context of their national interests, they tend to attribute the main reason to the bad intentions and evil character of others.

Thus, the correct answer is D.