Answer:
d. a difference in access to relevant knowledge.
Explanation:
"The theory of asymmetric information was developed in the 1970s and 1980s as a plausible explanation for common phenomena that mainstream general equilibrium economics couldn't explain. In simple terms, the theory proposes that an imbalance of information between buyers and sellers can lead to inefficient outcomes in certain markets."
Reference: Ross, Sean. “The Theory of Asymmetric Information in Economics.” Investopedia, Investopedia, 4 Oct. 2019