A technician is checking a car for loose and erratic steering. When an assistant moves the steering wheel left and right, he notices the entire steering rack moving back and forth about one-half inch. He checks the tightness of the rack mounting bolts and finds that they are torqued to specifications. What could be the problem?a. worn inner tie-rod endb. worn outer tie-rod endc. worn steering U-joint [coupler]d. worn rack mount bushings