Transitional species are the species that are considered as intermediate. They are the species in between two contrasting species.
Archaeopteryx is considered as a transitional species because their fossils are in between dinosaurs and modern birds. Tiktaalik are also considered as transitional species because they are in between fish and and early tetrapod.
Transitional species supports the theory of evolution. The fossils found are considered as evidence for evolution. Transitional fossils are debris of species that are present in between ancestral species and modern species.
Answer - Options 1, 2, 3, and 4.
The last option is not correct. Transitional species does not contradict the theory of evolution. It supports the theory of evolution. Transitional fossils are evidence for evolution. Transitional fossils are debris of species that are present in between ancestral species and modern species.