504
The 1991 ATP Championship Series , Single Week were part of the 1991 ATP Tour , the elite tour for professional men 's tennis organised by the Association of Tennis Professionals .
 organization: Association of Tennis Professionals
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: location, person, organization 
Text: {0} 
 Entities: Association of Tennis Professionals 
Answer:
 organization: Association of Tennis Professionals