Question: who was the youngest president to be elected
[{'answer': 'Theodore Roosevelt', 'provenance': [{'wikipedia_id': '11262088', 'title': 'List of presidents of the United States by age', 'start_paragraph_id': 3, 'start_character': 190, 'end_paragraph_id': 3, 'end_character': 208, 'bleu_score': 1.0, 'section': 'Section::::Age of presidents.\n'}]}, {'answer': 'John F. Kennedy', 'provenance': [{'wikipedia_id': '11262088', 'title': 'List of presidents of the United States by age', 'start_paragraph_id': 3, 'start_character': 401, 'end_paragraph_id': 3, 'end_character': 416, 'bleu_score': 1.0, 'section': 'Section::::Age of presidents.\n'}]}, {'provenance': [{'wikipedia_id': '11262088', 'title': 'List of presidents of the United States by age', 'start_paragraph_id': 3, 'start_character': 0, 'end_paragraph_id': 3, 'end_character': 531, 'bleu_score': 0.7851324905260421, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 7260977036792147267}, 'section': 'Section::::Age of presidents.\n'}]}, {'provenance': [{'wikipedia_id': '11262088', 'title': 'List of presidents of the United States by age', 'section': 'Section::::Age of presidents.\n', 'start_paragraph_id': 3, 'end_paragraph_id': 3, 'meta': {'evidence_span': ['Theodore Roosevelt', "The median age upon accession to the presidency is 55 years and 3 months. This is how old Lyndon B. Johnson was at the time of his inauguration. The youngest person to assume the office was Theodore Roosevelt, who became president at the age of , following William McKinley's assassination; th", "William McKinley's assassination; the oldest was Donald Trump, who was old at his inauguration. The youngest person to be elected preside"]}}]}, {'provenance': [{'wikipedia_id': '11262088', 'title': 'List of presidents of the United States by age', 'section': 'Section::::Oldest living U.S. presidents.\n', 'start_paragraph_id': 10, 'end_paragraph_id': 10, 'meta': {'evidence_span': ['Theodore Roosevelt', 'Of the 44 persons who have served as president, 24 have become the oldest such individual of their time, with one, William Howard Taft, doing so twice. Herbert Hoover held the distinction for the longest period of any, from the death of Calvin Coolidge in January 1933 until his own death 31 years later. Lyndon B. Johnson held it for the shortest, from the death of Harry S. Truman in December 1972 until his own death only 27 days la']}}]}]