Solution:Concept: Organs or skeletal elements of animals and organisms are examples of homologous structures. By virtue of their link to a common ancestor, these organs exhibit similarities.
However, these structures don't exactly resemble one another or perform the same function. The most crucial characteristic is that they are structurally similar, as suggested by their name.
Homologous Structures Examples
The leg of a dog, the wing of a bird or a bat, the flipper of a dolphin or whale, and the arm of a human. These organs are homologous because, although being different and serving different functions, they are comparable and have similar characteristics.
In contrast to analogous organs, which have different structures depending on the species, homologous organs have the same structural plan. Analogous organs always carry out the same duties while homologous organs carry out different ones.
Hence, option 4 is the correct answer.