Question: what age did the williams sisters start playing tennis
[{'answer': 'an early age', 'provenance': [{'wikipedia_id': '578943', 'title': 'Williams sisters', 'start_paragraph_id': 1, 'start_character': 256, 'end_paragraph_id': 1, 'end_character': 268, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '578943', 'title': 'Williams sisters', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 1816, 'bleu_score': 0.9214185405841561, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 11997777147304463326}, 'section': 'Section::::Abstract.'}]}]