Question: who was the photographer that was the leader and catalyst for photography as an art form
[{'answer': 'Alfred Stieglitz', 'provenance': [{'wikipedia_id': '364788', 'title': 'Alfred Stieglitz', 'start_paragraph_id': 0, 'start_character': 0, 'end_paragraph_id': 0, 'end_character': 16, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '364788', 'title': 'Alfred Stieglitz', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 445, 'bleu_score': 0.9561377777523261, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 11036360425608693217}, 'section': 'Section::::Abstract.'}]}]