Question: when does elena turn into a vampire in vampire diaries
[{'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.'}]}, {'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': 17999346961155680202}, 'section': 'Section::::Abstract.'}]}]