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.

Context : ``Devil's Triad'' is the tenth episode of the eleventh season of the American police procedural drama NCIS, and the 244th episode overall. 
Question : Of what series is Devil's Triad a part of?
series

Context : Joshua James Guppey (August 27, 1820 -- December 8, 1893) was a military officer in the Union Army during the American Civil War, judge, school superintendent and politician. 
Question : What was the war that Joshua James Guppey fought in?
conflict

Context : The Marder I was developed in May 1942 by Major Alfred Becker. 
Question : What year was Marder I introduced?

service entry