The right answer is A.
A transitional form is a living or fossil species that has a mosaic of characters from two other species or groups of species.
In the past, evolutionists have wrongly considered that some organisms with mosaic characters are intermediate forms in evolution between two other species or taxa. These species were considered to retain primitive attributes of their home group while presenting new features that will be found in the species they were evolving. These conceptions are nebulous and arbitrary.
