Final answer:
Primary mandibular crowns, or baby teeth, are smaller than permanent crowns as they need to fit within a child's smaller jaw. The jaws grow to accommodate the larger, stronger permanent teeth designed for adult use.
Step-by-step explanation:
The question is asking about the size comparison between primary mandibular crowns, which are also known as baby teeth or deciduous teeth, and permanent crowns which replace them. Primary mandibular crowns are generally B) Smaller than permanent crowns. This is because primary teeth are meant for a smaller jaw size of children and need to be accommodated within the limited space of the growing jaw.
As children grow, their jaws also enlarge to accomodate larger permanent teeth which are designed to last a lifetime. Permanent teeth not only replace primary teeth in terms of space but also come with a larger and stronger structure to accommodate the needs of adult eating and chewing functions.