Learning Theorists Have Researched the Application of Models of Classical

Learning theorists have researched the application of models of classical conditioning to both categorical and causal learning. Why?

A) Learning theorists treat effects that challenge the generality of laws of learning as opportunities to improve them.
B) Research demonstrating the ability to generalize the laws of learning from invertebrates to vertebrates has led psychologists to believe that it is possible to develop a single theory that will explain all learning phenomena.
C) The apparent differences between classical and instrumental conditioning have recently been demonstrated to be minimal.
D) Psychologists of human learning and memory have agreed that classical conditioning models provide parsimonious explanations of complex as well as simple forms of learning.