<Li> Intelligent (UK Holdings) Limited </Li> <Ul> <Li> Garda </Li> </Ul> <Ul> <Li> ADT Security Services </Li> <Li> Allied Universal </Li> <Li> G4S Secure Solutions </Li> <Li> Inter-Con Security </Li> <Li> Monitronics </Li> <Li> Pinkerton Security </Li> <Li> Vivint </Li> </Ul> <Li> ADT Security Services </Li>

Who is the largest security company in the united states
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