Which of the following is not a compelling explanation for childhood amnesia?

Which of the following is not a compelling explanation for childhood amnesia?
a)  The amygdala and the hippocampus synchronize with one another to encode episodic memories, and both structures take approximately 3 years to develop to maturity.
b)  Social conventions for encoding, reporting, and retrieving information take time to develop; young children lack the social development necessary for effective memory development.
c)  Children lack a well-developed self-schema and other cognitive schemas through which to interpret, categorize, and mentally "file" events that happen in their early years.
d)  The prefrontal cortex is involved in memory formation and storage, but the prefrontal cortex takes years to develop.