You are presented with the quiz "What is bilaterally symmetrical and a protostome?" 

But you don't know the answer, so you turn to your teacher to ask for hints. He says that "mollusks are invertebrates such as the common snail" and "mollusks are bilateraly symetrical and are protostomes". 

So, what's the best answer to the question?


 

      the common snail     