AT&T (NYSE: T) and Time Warner, Inc. (NYSE: TWX) have responded to 13 Senators who question their merger, explaining in detail their stance that the combined company would spur innovation without hurting consumer choice. “This deal will increase competition and accelerate the innovation/investment cycle, all to the benefit of American consumers,” reads the letter, signed by AT&T Executive VP – Federal Relations Tim McKone and Steve Vest, Time Warner’s senior VP of global public policy. The…