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In addition to the soloist performances , members of the Pennsylvania Ballet were cast as the corps de ballet , backdrop for the main actors ' performances .
 Pennsylvania Ballet
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:
 Pennsylvania Ballet