24598
Similarly , all the statements listed below which require choice or some weaker version thereof for their proof are unprovable in ZF , but since each is provable in ZF plus the axiom of choice , there are models of ZF in which each statement is true .
 None
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 None