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The NASA Clean Air Study has been led by the National Aeronautics and Space Administration ( NASA ) in association with the Associated Landscape Contractors of America ( ALCA ) .
 NASA, NASA, Associated Landscape Contractors of America
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 NASA, NASA, Associated Landscape Contractors of America