We Have Often Heard of the Myth That We Only

We have often heard of the myth that we only use 10% of our brain. Why might we be convinced that this is true?

A) there are no neurotransmitters in much of the brain
B) we share 10% of our cortex with lower animals
C) a great deal of cortex can be removed with only a small loss of function
D) brain scans reveal that only 10% of the brain is active at any given time
E) we have only mapped about 10% of the brain