Question: what grade were eric harris and dylan klebold in
[{'answer': 'twelfth grade'}, {'provenance': [{'wikipedia_id': '378561', 'title': 'Eric Harris and Dylan Klebold', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 480, 'bleu_score': 0.647637320967547, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 17680037665204485702}, 'section': 'Section::::Abstract.'}]}]