Answer:
The market structure that Keith's company uses is monopolistic competition.
Step-by-step explanation:
In monopolistic competition, there are many firms in the market, the price is mostly determined by market forces, and as a result, the companies try to sell products that are different in some way.
In this case, Keith's company competitors are trying to use a pricing strategy to increase their market share. They are trying to compensate loss of revenue from the lower prices, with a higher sales volume.