What Does the Assumption of Rational Self-Interest Mean

Multiple Choice

What does the assumption of rational self-interest mean?  

A)  that economic decision makers have no concern for the welfare of others 
B)  that economic decision makers consider the welfare of others to be more important than their own happiness 
C)  that economic decision makers know with certainty which choice will have the best result 
D)  that economic decision makers make reasonable decisions based on their expectations of results