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Clearly , their corporate culture has suffered - - 25 years ago , MCI was the brawling upstart in the telecom industry , constantly challenging AT & T ' s right to exist , much less to monopolize the phone system .
 their, MCI, the brawling upstart in the telecom industry , constantly challenging AT & T ' s right to exist , much less to monopolize the phone system, the telecom industry, AT & T
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: organization, person, geographical social political, vehicle, location, weapon, facility 
Text: {0} 
Answer:
 their, MCI, the brawling upstart in the telecom industry , constantly challenging AT & T ' s right to exist , much less to monopolize the phone system, the telecom industry, AT & T