Question: landform that separates vietnam from cambodia and laos
[{'answer': 'Dangrek Mountains plateau', 'provenance': [{'wikipedia_id': '5429', 'title': 'Geography of Cambodia', 'start_paragraph_id': 15, 'start_character': 277, 'end_paragraph_id': 15, 'end_character': 302, 'bleu_score': 1.0, 'section': 'Section::::General topography.\n'}]}, {'provenance': [{'wikipedia_id': '5429', 'title': 'Geography of Cambodia', 'start_paragraph_id': 15, 'start_character': 0, 'end_paragraph_id': 15, 'end_character': 579, 'bleu_score': 0.978606533029418, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 8513847085770694735}, 'section': 'Section::::General topography.\n'}]}]