Question: who determined the mass to charge ratio of an electron
[{'answer': 'J.J. Thomson'}, {'provenance': [{'wikipedia_id': '3957360', 'title': 'Mass-to-charge ratio', 'start_paragraph_id': 16, 'start_character': 0, 'end_paragraph_id': 16, 'end_character': 942, 'bleu_score': 0.9715305700167061, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 5225936819551554543}, 'section': 'Section::::History.\n'}]}]