DeConinck Soup Co. found that its canned nacho cheese sauce was too spicy for Americans in the East and not spicy enough for those in the West and Southwest. Today, DeConinck's plants in Texas and California produce a spicier nacho cheese sauce than what is produced in the other plants. DeConinck's is using segmentation.

D). Geographic segmentation.

Explanation:

Geographic segmentation is defined as the marketing strategy that primarily aims to target the distinct choice preferences of the customers across a specific region or area. DeConinck Co. is employing this strategy to understand the consumer needs and cater to the different types of demands of their customers residing across the region by producing and marketing products accordingly(spicier nachos for the Customers of Western and Southwestern Americans and less spicy nachos for the Eastern region). Thus, option D is the correct answer.