Question: when does lucas find out dan killed keith
[{'answer': 'Season 4', 'provenance': [{'wikipedia_id': '2818272', 'title': 'Lucas Scott', 'start_paragraph_id': 19, 'start_character': 3, 'end_paragraph_id': 19, 'end_character': 11, 'bleu_score': 1.0, 'section': 'Section::::Storylines.:Early seasons.\n'}]}, {'provenance': [{'wikipedia_id': '2818272', 'title': 'Lucas Scott', 'start_paragraph_id': 19, 'start_character': 0, 'end_paragraph_id': 19, 'end_character': 3240, 'bleu_score': 0.9966969333935651, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 11063179885131468018}, 'section': 'Section::::Storylines.:Early seasons.\n'}]}]