Question: who was it that described the structure of dna
[{'answer': 'James Watson and Francis Crick', 'provenance': [{'wikipedia_id': '7955', 'title': 'DNA', 'start_paragraph_id': 64, 'start_character': 439, 'end_paragraph_id': 64, 'end_character': 469, 'bleu_score': 1.0, 'section': 'Section::::Properties.:Alternative DNA structures.\n'}]}, {'answer': 'James Watson', 'provenance': [{'wikipedia_id': '7955', 'title': 'DNA', 'start_paragraph_id': 5, 'start_character': 120, 'end_paragraph_id': 5, 'end_character': 132, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': 'Francis Crick', 'provenance': [{'wikipedia_id': '7955', 'title': 'DNA', 'start_paragraph_id': 5, 'start_character': 102, 'end_paragraph_id': 5, 'end_character': 115, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '7955', 'title': 'DNA', 'start_paragraph_id': 5, 'start_character': 0, 'end_paragraph_id': 5, 'end_character': 737, 'bleu_score': 0.8975104411150511, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 17184954588931600367}, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '7955', 'title': 'DNA', 'section': 'Section::::Abstract.', 'start_paragraph_id': 5, 'end_paragraph_id': 5, 'meta': {'evidence_span': ['DNA was first isolated by Friedrich Miescher in 1869. Its molecular structure was first identified by Francis Crick and James Watson at the Cavendish Laboratory within the University of Cambridge in 1953, whose model-building efforts were guided by X-ray diffraction data acquired by Raymond Gosling, who was a post-graduate student of Rosalind Franklin.', 'DNA was first isolated by Friedrich Miescher in 1869. Its molecular structure was first identified by Francis Crick and James Watson at the Cavendish Laboratory within the University of Cambridge in 1953, whose model-building efforts were guided by X-ray diffraction data acquired by Raymond Gosling, who was a post-graduate student of Rosalind Franklin. DNA is used by researchers as a molecular tool to explore physical laws and theories, such as the ergodic theorem and the theory of elasticity. The unique material properties of DNA have made it an attractive molecule for material scientists and engineers interested in micro- and nano-fabrication. Among notable advances in this field are DNA origami and DNA-based hybrid materials.', 'Its molecular structure was first identified by Francis Crick and James Watson at the Cavendish Laboratory']}}]}, {'provenance': [{'wikipedia_id': '13928', 'title': 'HersheyChase experiment', 'section': 'Section::::Discussion.:Other experiments.\n', 'start_paragraph_id': 20, 'end_paragraph_id': 20, 'meta': {'evidence_span': ['Once the HersheyChase experiment was published, the scientific community generally acknowledged that DNA was the genetic code material. This discovery led to a more detailed investigation of DNA to determine its composition as well as its 3D structure. Using X-ray crystallography, the structure of DNA was discovered by James Watson and Francis Crick with the help of previously documented experimental evidence by Maurice Wilkins and Rosalind Franklin. Knowledge of the structure of DNA led scientists to examine the nature of genetic coding and, in turn,', 'the structure of DNA was discovered by James Watson and Francis Crick']}}]}, {'provenance': [{'wikipedia_id': '395970', 'title': 'James Watson (disambiguation)', 'section': 'Section::::Abstract.', 'start_paragraph_id': 1, 'end_paragraph_id': 1, 'meta': {'evidence_span': ['James Watson (born 1928) is an American biologist and chemist, the co-discoverer of the double-helical structure of DNA, awarded the 1962 Nobel Prize in Physiology or Medicine.', 'James Watson (born 1928) is an American biologist and chemist, the co-discoverer of the double-helical structure of DNA, awarded the 1962 Nobel Prize in Physiology or Medicine.']}}]}]