232667
Among the tobacco-specific nitrosamines , 4 - ( methylnitrosamino ) -1 - ( 3-pyridyl ) -1 - butanone ( NNK ) and N ' - nitrosonornicotine ( NNN ) are the most carcinogenic .
 None
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:  
Answer:
 None