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A similar argument is made by David Marks who argues that IQ differences correlate well with differences in literacy suggesting that developing literacy skills through education causes an increase in IQ test performance .
 David Marks
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: media, plant, vehicle, astronomical object, time, disease, animal, location, person, organization, mythical figure, food, biology, geographical phenomenon, instrument, event 
Text: {0} 
Answer:
 David Marks