Question: Name the military unit whose garrison is Arlington County, Virginia and command structure is United States Department of Defense?
SPARQL query:
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX onto: <http://dbpedia.org/ontology/>
SELECT DISTINCT ?uri WHERE {?uri onto:garrison <http://dbpedia.org/resource/Arlington_County,_Virginia> . ?uri onto:commandStructure <http://dbpedia.org/resource/United_States_Department_of_Defense>  . ?uri rdf:type onto:MilitaryUnit}