Question: when did the army switch from bdu to acu
[{'answer': 'June 2004', 'provenance': [{'wikipedia_id': '1211313', 'title': 'Army Combat Uniform', 'start_paragraph_id': 2, 'start_character': 18, 'end_paragraph_id': 2, 'end_character': 27, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]