Question: where would phase contrast microscopy improve image quality
[{'answer': 'cellular structures', 'provenance': [{'wikipedia_id': '8008377', 'title': 'Phase-contrast microscopy', 'start_paragraph_id': 4, 'start_character': 16, 'end_paragraph_id': 4, 'end_character': 35, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]