Final answer:
Ornithischian dinosaurs were diverse herbivores with a bird-hipped pelvis, but birds are descended from the theropod group of the Saurischian 'lizard-hipped' dinosaurs, which included both carnivorous and herbivorous species. Not all ornithischians were bipedal, nor were all saurischians quadrupedal. Thus, the option a is the correct answer.
Step-by-step explanation:
The Ornithischia, with their characteristic 'bird-hipped' pelvis, were a diverse group of herbivorous dinosaurs. They lived throughout the Mesozoic era and included various species like the ankylosaur armored tanks and horned dinosaurs such as Triceratops. Importantly, birds did not evolve from the Ornithischian lineage despite the similar pelvic structure. On the other hand, Saurischia, or 'lizard-hipped' dinosaurs, diverged into long-necked herbivores and bipedal predators, the latter of which, the theropods, ultimately gave rise to birds. The Saurischia included both herbivorous and carnivorous dinosaurs, some with colossal sizes, such as Argentinosaurus, indicating that not all saurischians were carnivorous as some were herbivorous giants.
Additionally, birds and feathers are thought to have evolved from the maniraptoran theropod dinosaurs, a subgroup of the Saurischia. This is supported by substantial evidence such as the structure of the hip and wrist bones, and feathered fossils of theropods like Archaeopteryx, bridging the gap between dinosaurs and modern birds. Both ornithischian and saurischian dinosaurs are known to have provided parental care and not all ornithischian dinosaurs were bipedal, nor were all saurischian dinosaurs quadrupedal, thus challenging the options presented in the student's question.