Question: who is the father of christina yangs baby
[{'answer': 'Preston Burke', 'provenance': [{'wikipedia_id': '7687021', 'title': 'Cristina Yang', 'start_paragraph_id': 1, 'start_character': 734, 'end_paragraph_id': 1, 'end_character': 747, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '7687021', 'title': 'Cristina Yang', 'start_paragraph_id': 5, 'start_character': 0, 'end_paragraph_id': 5, 'end_character': 1234, 'bleu_score': 0.806270351253994, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 12051802671249809326}, 'section': 'Section::::Storylines and character.\n'}]}]