Final answer:
Birds and butterflies are classified differently primarily due to anatomical differences, such as birds' feathers and lightweight skeletons versus butterflies' scaled wings and exoskeletons. These differences reflect their unrelated evolutionary histories and distinctive adaptations to their environments. The correct option is C.
Step-by-step explanation:
Birds and butterflies were placed into different groups within the biological classification systems because of differences in anatomical structures. Birds have several unique physical attributes such as feathers, a beak with no teeth, and a specialized digestive system.
In contrast, butterflies have exoskeletons, wings covered in scales, and undergo complete metamorphosis during their life cycle. These anatomical differences are significant enough to classify birds and butterflies into separate groups. Birds belong to the class Aves, which is characterized by attributes ideal for flight, such as a lightweight skeleton and powerful muscles for flapping wings. Meanwhile, butterflies are part of the order Lepidoptera, which includes insects with two pairs of wings covered with minute scales.
In addition to anatomical differences, birds and butterflies differ in other fundamental areas such as genetic material and evolutionary history, like the long-distance migration behavior observed in some butterfly species. Moreover, their adaptations to environmental niches and methods of obtaining food also differ sharply. Birds, for instance, may eat a variety of foods using their beaks while butterflies typically feed on nectar or other plant substances using their proboscis.
Hence, Option C is correct.