Question: which batsman has the highest average score in test match
[{'answer': "Australia 's Sir Donald Bradman", 'provenance': [{'wikipedia_id': '18933273', 'title': 'Batting average', 'start_paragraph_id': 4, 'start_character': 176, 'end_paragraph_id': 4, 'end_character': 207, 'bleu_score': 1.0, 'section': 'Section::::Cricket.\n'}]}]