Question: when does elena turn into a vampire in the tv series
[{'answer': 'season four', 'provenance': [{'wikipedia_id': '24376684', 'title': 'Elena Gilbert', 'start_paragraph_id': 26, 'start_character': 3, 'end_paragraph_id': 26, 'end_character': 14, 'bleu_score': 1.0, 'section': 'Section::::Television series.:Storyline.:Season 4.\n'}]}, {'answer': 'fourth season', 'provenance': [{'wikipedia_id': '24376684', 'title': 'Elena Gilbert', 'start_paragraph_id': 2, 'start_character': 554, 'end_paragraph_id': 2, 'end_character': 567, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': "In the television series 's fourth season"}, {'provenance': [{'wikipedia_id': '24376684', 'title': 'Elena Gilbert', 'start_paragraph_id': 26, 'start_character': 0, 'end_paragraph_id': 26, 'end_character': 1277, 'bleu_score': 0.991130601392713, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 12836388912322342027}, 'section': 'Section::::Television series.:Storyline.:Season 4.\n'}]}, {'provenance': [{'wikipedia_id': '24376684', 'title': 'Elena Gilbert', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 1413, 'bleu_score': 0.9290011507847181, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 12836388912322342027}, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '24376684', 'title': 'Elena Gilbert', 'section': 'Section::::Abstract.', 'start_paragraph_id': 2, 'end_paragraph_id': 2, 'meta': {'evidence_span': ["She took the cure and became human again towards the end of the sixth season. In the finale of the sixth season, Kai linked Elena to Bonnie's life by magic. Elena will only wake up when Bonnie dies in around 60 years. She was locked inside the Salvatore tomb, then relocated to a warehouse in Brooklyn, New York in the seventh season, then back to Mystic Falls. In late 2016, when it was announced that the eighth season would be the final season, Dobrev was in talks about returning to the television series to reprise her role in the final episode. After much speculation.", "In the television series's fourth season, Elena becomes a vampire", 'fourth season']}}]}]