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As of 2018 the largest low-carbon energy sources globally were hydropower and nuclear power , with the latter providing over 50 % of low-carbon power alone in United States and European Union .
 United States, European Union
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:
 United States, European Union