45703
Other radio detectors invented for wireless telegraphy , such as the Fleming valve ( 1904 ) and the crystal detector ( 1906 ) also proved able to rectify AM signals , so the technological hurdle was generating AM waves ; receiving them was not a problem .
 person: Fleming
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: Fleming 
Answer:
 person: Fleming