The example of similar structures that indicates that species are related is forelimbs of bats and dogs. Option B is correct.
What is homologous structure ?
This structure is an example of a homologous structure, which may have distinct functions but a shared evolutionary ancestor. For example, dogs and bats have distinct adaptations for their forelimbs (legs for walking, whereas bats have wings for flight), yet the fundamental skeletal structure of both species is identical, indicating a shared ancestor.
So, The example of similar structures that indicates that species are related is forelimbs of bats and dogs.