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They make their way through the United States to Canada on the Underground Railroad with the help of Alexander Milton Ross , a Canadian abolitionist .
 person: Alexander Milton Ross
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: Alexander Milton Ross 
Answer:
 person: Alexander Milton Ross