Answer:
B no symmetry→radial symmetry→bilateral symmetry→backbone
Step-by-step explanation:
In the evolution of body symmetry, radially symmetrical animals evolved from animals that completely lack body symmetry while bilaterally symmetrical animals evolved from radially symmetrical ones as they keep adapting to their changing environments.
In addition, only bilaterally symmetrical animals have backbones.
Hence, the direction of adaptation from earliest to most recent would be from asymmetry to radial symmetry to bilateral symmetry to backbone.
The correct option is B.