Question: when did towers perrin and watson wyatt merger
[{'answer': 'January 4 , 2010', 'provenance': [{'wikipedia_id': '23421725', 'title': 'Towers Watson', 'start_paragraph_id': 3, 'start_character': 28, 'end_paragraph_id': 3, 'end_character': 44, 'bleu_score': 1.0, 'section': 'Section::::Overview.\n'}]}, {'provenance': [{'wikipedia_id': '23421725', 'title': 'Towers Watson', 'start_paragraph_id': 3, 'start_character': 0, 'end_paragraph_id': 3, 'end_character': 534, 'bleu_score': 0.978138775770484, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 170690381755159719}, 'section': 'Section::::Overview.\n'}]}]