270438
All three designs were driven by the need to provide wide fields of fire in the absence of effective synchronisation gear that would allow safe firing of guns through the propeller disc .
 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