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The airport was established in 1919 by Reserve Lieutenant Johnny Johnston after returning from World War I. Much of the early aerial photography of the then-rural Santa Clara Valley , now better known as Silicon Valley , was taken on flights from the Alum Rock Airport .
 location: Valley; location: Silicon Valley; location: Alum Rock
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: Valley, Silicon Valley, Alum Rock 
Answer:
 location: Valley; location: Silicon Valley; location: Alum Rock