Final answer:
Infantile amnesia, the inability to remember events from early childhood, is due to undeveloped brain structures, namely the hippocampus and prefrontal cortex. These structures are crucial in memory consolidation and complex cognitive functions.
Step-by-step explanation:
Most people cannot recall events before age 3 because of infantile amnesia, caused by the lack of development of the brain structures, the hippocampus and prefrontal cortex. Thus, the correct answer is: a) Hippocampus; prefrontal cortex. The hippocampus is involved in the encoding and consolidation of new memories, while the prefrontal cortex is associated with complex cognitive behavior and the expression of personality. This can be related to the Atkinson-Shiffrin model which states that we process information through three systems: sensory memory, short-term memory, and long-term memory.
The importance of the hippocampus in memory formation was evidenced by the case of patient HM, who suffered from severe anterograde amnesia after having both medial temporal lobes removed to treat epilepsy. Patient HM was unable to form new long-term memories, which showcases the critical role of the hippocampus in memory consolidation.