The correct answer is - 5. Tortoises and snails have analogous organs, and they aren't evolutionary related.
The similarities of the tortoises and the snails are example of parallel evolution, where both species totally unrelated, have developed similar mechanisms to cope with the environment, in their case, the outer shell for protection against predators.
Both organisms have similar functioning organs, but they are not evolutionary related thus that makes them have analogous organs.
The tortoises are part of the reptilians, and even though they have an outer shell, they also have internal bone structure. The snails on the other hand, are not even vertebrates, they are in fact invertebrates, so the outer shell is the only bone structure they have, with no internal body structure whatsoever.
