According to Simon's Theory of Bounded Rationality,why Do Humans Tend

According to Simon's theory of bounded rationality,why do humans tend to make irrational decisions

A)  because we make decisions more difficult than they need to be 
B)  because we use simple strategies and focus on limited information 
C)  because we have logic systems that are only useful in natural environments 
D)  because we are too guided by our emotions