For a segmentation strategy to be successful, the customers in the segment must react similarly and positively to the firm's marketing mix. In other words, the market segment must be

A) substantial.
B) perceptive.
C) identifiable.
D) reachable.
E) responsive.

For a segmentation strategy to be successful, the market segment must be responsive, meaning that the customers in the segment react similarly and positively to the firm's marketing mix. This is the most important criterion as it directly relates to the effectiveness of the strategy. However, the other criteria (substantial, identifiable, and reachable) are also important in ensuring that the segment is viable and can be effectively targeted by the firm. Perceptiveness, while desirable, is not a necessary criterion for a successful segmentation strategy.