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.
--------
Question: Context : According to Nielsen Media Research, ``Leslie's House'' was seen by 4.35 million viewers, a slight drop from the previous episode, ``The Set Up''. 
Question : To which series does Leslie's House belong?

Answer: series


Question: Context : Veronika Martinek (born 3 April 1972) is a former professional female tennis player playing for Germany. 
Question : Which sex is Veronika Martinek?

Answer: sex or gender


Question: Context : The Pietà for Vittoria Colonna is a black chalk drawing on cardboard (28.9×18.9 cm) by Michelangelo Buonarroti, dated to about 1538--44 and kept at the Isabella Stewart Gardner Museum in Boston. 
Question : What is the name of the place where Pietà for Vittoria Colonna can be found?

Answer:
collection