Plants that do not have well-differentiated body designs fall into the group called:
A. Pteridophyta
B. Thallophyta
C. Bryophyta
D. Gymnosperm
A well-differentiated body design in plants is the division of the plant body into roots, stems, and leaves.
This differentiation is absent in Algae and hence they are grouped under Thallophyta meaning undifferentiated plant body or thallus-like plant body.
So, the correct option is 'B'