Question: the carolingian era was marked by what type of social system
[{'answer': 'feudal systems'}, {'provenance': [{'wikipedia_id': '62229', 'title': 'Carolingian Empire', 'start_paragraph_id': 8, 'start_character': 0, 'end_paragraph_id': 8, 'end_character': 754, 'bleu_score': 0.925850041870744, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 3449574159920683946}, 'section': 'Section::::History.:Rise of the Carolingians (c. 732–768).\n'}]}]