Flatworms were the earliest group to have a(n) _____.
a. eye
b. notochord
c. primitive central nervous system
d. radial symmetry
e. fully developed brain
Answer: C
Flatworms were the earliest group to have a(n) _____.
a. eye
b. notochord
c. primitive central nervous system
d. radial symmetry
e. fully developed brain