Final answer:
The correct option is D). The plates of Stegosaurus functioned as solar panels/radiators or for display, aiding in temperature regulation or as part of mating and intimidating displays.
Step-by-step explanation:
The plates of Stegosaurus primarily functioned as solar panels/radiators or for display. While there has been debate about their exact purpose, most scientists now agree the plates were likely used to regulate body temperature like a solar panel collecting and dissipating heat or as display structures for attracting mates or intimidating other animals. They were not strictly defensive armor as their placement and structure would have offered limited protection.