Question: when do meredith and derek officially became a couple
[{'answer': 'season seven', 'provenance': [{'wikipedia_id': '7619908', 'title': 'Derek Shepherd', 'start_paragraph_id': 9, 'start_character': 443, 'end_paragraph_id': 9, 'end_character': 455, 'bleu_score': 1.0, 'section': 'Section::::Storyline.\n'}]}, {'provenance': [{'wikipedia_id': '7619908', 'title': 'Derek Shepherd', 'start_paragraph_id': 9, 'start_character': 0, 'end_paragraph_id': 9, 'end_character': 1254, 'bleu_score': 0.9625900279070481, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 13607036460462511006}, 'section': 'Section::::Storyline.\n'}]}]