For price discrimination to work ________.

A、the market must be segmentable and the segments must show similar intensities of demand;
B、 members in the lower-price segment must be able to resell the product to the higher-price segment;
C、 competitors must be able to undersell the firm in the higher-price segment;
D、 the practice must not breed customer resentment and ill will;
E、 the extra revenue derived from price discrimination must not exceed the cost of segmenting and policing the market