Answer:
D. studying cultural differences
Step-by-step explanation:
Howard Gardner is well known for his famous work with multiple intelligences.
Howard Earl Gardner is a developmental psychologist. Gardner has done many research work on multiple intelligence. According to him, intelligence is greater than IQ because when productivity is not there, the IQ is not equated to the intelligence.
Gardner's theory of Multiple Intelligence says that people in order to have all the abilities and talents in the world, they does not have only intellectual capacity, but have a list of intelligence which includes interpersonal, musical, linguistic intelligences and spatial-visual.
For this, Gardner did several studies and gathered evidences from many studies including effects of brain damage on intelligence, researching developmental influences and also studying prodigies.
Thus Gardner for his theory of multiple intelligences did not gathered evidence from --
D. studying cultural differences