Classify the relation of question with context to one of these categories: 1) award received, 2) based on, collection, 3) conflict, 4) constellation, 5) convicted of, 6) date of death, 7) director, 8) drafted by, 9) educated at, 10) medical condition, 11) military branch, 12) narrative location, 13) occupation, 14) original network, 15) parent company, 16) point in time, 17) production company, 18) residence, 19) series, 20) service entry, 21) sex or gender, 22) spouse, 23) standards body question.

[EX Q]: Context : Antonio Reali was born on 31 March 1891 in Ozegna, the Kingdom of Italy. 
Question : In what war did Antonio Reali fight in?
[EX A]: conflict

[EX Q]: Context : Philipp Krementz was born, the son of a butcher, in Koblenz in 1837 and began to study theology in Bonn, which he continued in Munich in 1839. 
Question : What was the death date of Philipp Krementz?
[EX A]: date of death

[EX Q]: Context : The Buk missile system (Russian: ``Бук''; ``beech'' (tree), /bʊk/) is a family of self-propelled, medium-range surface-to-air missile systems developed by the Soviet Union and its successor state, the Russian Federation, and designed to fight cruise missiles, smart bombs, fixed- and rotary-wing aircraft, and unmanned aerial vehicles. 
Question : What year was Buk missile system commissioned?
[EX A]:
service entry