Final answer:
Analogous structures in animals are best demonstrated by bird wings and insect wings because both serve the same function of flight but have different embryonic origins, indicating they evolved independently.
Step-by-step explanation:
The best example demonstrating analogous structures in animals is C. Bird wings and insect wings. Analogous structures are those that have similar functions but evolved independently, often because of similar environmental pressures, not because of a recent common ancestor. Bird and insect wings serve the same function – flight – but these animals belong to very different evolutionary lineages and the embryonic origin of their wings is completely different, indicating they are analogous.
Other examples of analogous structures include the streamlined bodies and fins seen in sharks and dolphins. Despite being different in evolutionary terms, their body shapes have evolved convergently to adapt to their aquatic environments. However, structures like the bones in a whale's flipper being homologous to the bones in a human arm are not examples of analogous structures, as they have a common embryonic origin and suggest a shared evolutionary past.
Analogous structures are a result of convergent evolution, as seen with the wings of butterflies and birds or the fins of sharks and dolphins.