Over the past several years, like other auto manufacturers, General Motors (GM) has introduced many new models of sport utility vehicles (SUVs) in all of its major divisions. This proliferation of SUVs and an increase in gasoline prices have caused sales to level off. In response, General Motors offered rebates of up to $5,000, or no-interest financing, on selected models of SUVs. The largest rebates went to current owners of GM vehicles, so that they would replace their current vehicles with a GM model instead of switching to another brand. The rebates have been heavily advertised on national television. Profit margins per vehicle have shrunk as a result of these costly promotions. In what stage of the product life cycle is GM currently operating? A. Market establishment. B. Market introduction. C. Market growth. D. Market maturity. E. Sales decline