What is the most important implication about cognitive psychologists's ability to measure whether a function is cognitively impenetrable or not?

a. Cognitive psychologists require evidence from neuroscience to defend the claim a function is primitive

b. Cognitive psychology can only be explanatory by identifying a core set of cognitively penetrable functions

c. Cognitive impenetrability is the only first-order property studied by cognitive psychologists; all other properties are second-order

d. Cognitve psychologists can defend the claim a function is primitive without having to use methods of neuroscience to explain how the function works