Question: when did the nba start playing zone defense
[{'answer': '2002', 'provenance': [{'wikipedia_id': '1965453', 'title': 'Zone defense', 'start_paragraph_id': 6, 'start_character': 160, 'end_paragraph_id': 6, 'end_character': 164, 'bleu_score': 1.0, 'section': 'Section::::Basketball.\n'}]}, {'answer': 'the 2001 -- 2002 season'}, {'provenance': [{'wikipedia_id': '1965453', 'title': 'Zone defense', 'start_paragraph_id': 0, 'start_character': 0, 'end_paragraph_id': 0, 'end_character': 0, 'bleu_score': 1.0, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 1728760393060350610}, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '1965453', 'title': 'Zone defense', 'start_paragraph_id': 6, 'start_character': 0, 'end_paragraph_id': 6, 'end_character': 551, 'bleu_score': 0.9396430371117861, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 1728760393060350610}, 'section': 'Section::::Basketball.\n'}]}, {'provenance': [{'wikipedia_id': '52454088', 'title': 'Expansion of the National Basketball Association', 'section': 'Section::::Abstract.', 'start_paragraph_id': 1, 'end_paragraph_id': 1, 'meta': {'evidence_span': ['ho later relocated to Memphis in 2001), and New Orleans Pelicans in 2002.', "The expansion of the National Basketball Association has happened several times in the league's history since it began play in 1946. Some of the most recent examples of the expansion of the NBA are the Charlotte Hornets in 1988, Miami Heat in 1989, Vancouver Grizzlies in 1995 (who later relocated to Memphis in 2001), and New Orleans Pelicans in 2002."]}}]}, {'provenance': [{'wikipedia_id': '1965453', 'title': 'Zone defense', 'section': 'Section::::Basketball.\n', 'start_paragraph_id': 6, 'end_paragraph_id': 6, 'meta': {'evidence_span': ['In the National Basketball Association, zone defenses were prohibited until the 20012002 season, and most teams do not use them as a primary defensive strategy.', 'Association, zone defenses were prohibited until the 20012002 season,', 'Zone defenses are common in international, college, and youth competition. In the National Basketball Association, zone defenses were prohibited until the 20012002 season, and most teams do not use them as a primary defensive strategy. The NBA has a defensive three-second violation rule, which makes it more difficult for teams to play zone, since such defenses usually position a player in the middle of the key to stop penetration. The Dallas Mavericks under coach Rick Carlisle are an example of an NBA team that have regularly used zone defenses.']}}]}, {'provenance': [{'wikipedia_id': '5235900', 'title': 'Defensive three-second violation', 'section': 'Section::::Abstract.', 'start_paragraph_id': 1, 'end_paragraph_id': 1, 'meta': {'evidence_span': ['A defensive three-second violation, also known as illegal defense, is a basketball rules infraction in the National Basketball Association (NBA) introduced in the 2001-2002', 'A defensive three-second violation, also known as illegal defense, is a basketball rules infraction in the National Basketball Association (NBA) introduced in the 2001-2002 season. It is assessed when a member of the defending team spends more than three seconds in the free throw lane (also called the key, the 16-foot lane, or "in the paint") while not actively guarding an opponent. To be considered actively guarding, a defender must be within arm\'s length of an opponent and in a guarding position. A three-second count is suspended if:']}}]}]