What do the several cases of children who grew up in extreme social isolation, such as the case of Genie in 1970, suggest?
A Many of our mental capacities are learned through social interaction.
B Human intelligence is almost entirely determined by heredity.
C The effects of isolation at an early age are easily reversible if caught in time.
D The effects of extreme isolation in children are irreversible if the situation isn't corrected by the time the child is five years old.