Question

Which organism has a central brain

A.hydra
B.fish
C.sponge
D.flatworm
the real subject is science

Answer 1

Fish is your answer because the other organisms don't exactly have brains. Hope this helps :P

Answer 2

B. Fish 
While the flatworm was something sorta resembling a brain, it is not considered a central brain.
And hydra & sponges have no brains