Final answer:
Mandibular molars (option D) are wider mesiodistally than faciolingually because of their rectangular shape and their function to crush food.
Step-by-step explanation:
The question relates to the comparison of the mesiodistal (MD) width and the faciolingual (FL) diameter of teeth. Teeth that are wider mesiodistally than faciolingually are the mandibular molars (option D). The mandibular molars are the most posterior teeth, designed with several pointed cusps used to crush food. They generally have a more rectangular shape when observed from the occlusal perspective, making their MD dimension greater than that of FL.
Other options, such as the maxillary central incisors, mandibular canines, and maxillary premolars, typically do not have a greater MD width than FL diameter. The incisors and canines are more aligned for biting and tearing, and their shapes are not as rectangular and wide as the molars.