Which Organisms are Considered Most Primitive Based Upon the Structure

Question

Which organisms are considered most primitive based upon the structure of their limbs?  
A) Bats
B) Reptiles
C) Porpoises
D) Penguins
E) Birds

Accepted Answer

Reptiles are considered more primitive based on the structure of their limbs because they have a sprawling gait with limbs projecting out from the sides of their bodies. This is in contrast to more advanced animals such as birds, which have a more upright and streamlined limb structure adapted for flight. Bats, porpoises, and penguins are not considered primitive based on limb structure.