David has been a star representative and has personally serviced and developed all his accounts. recently, however, david's firm has grown steadily and the company's products and systems have become more and more complicated. in the past year or so, david and his sales colleagues have been changing their approach due to the sales growth and increasing product complexity. customer relationships are now being handled more and more by __________, which is typical of firms experiencing this kind of growth. manufacturer's representatives junior sales reps