Question: which branch of philosophy is concerned with fundamental questions about the nature of reality
[{'answer': 'Metaphysics', 'provenance': [{'wikipedia_id': '18895', 'title': 'Metaphysics', 'start_paragraph_id': 0, 'start_character': 0, 'end_paragraph_id': 0, 'end_character': 11, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]