How Would a Cell Phone Manufacturer Most Effectively Determine the Market

How would a cell phone manufacturer most effectively determine the market price of a new line of cell phones?

A) Put several of the new phones on sale at a watch store and see which sells most quickly.
B) Arrange to sell the phones in a number of diverse auctions.
C) Set the price of one phone higher than another and see which sells the most quickly.
D) Survey potential customers and retailers on what they think the price should be.
E) Ask executives from competing companies about what they think the price should be.