Read the following paragraph and answer the question. Give ONLY the answer, no other words or explanation.

For example:

Answer: <most likely answer, as short as possible>.

Paragraph: 
Example Problem: The density of steel is 9000. kg/m 3 and the density of water is 1000. kg/m 3 . If a cube of steel that is 0.100 m on each side is placed in a tank of water and weighed while under water, what is the apparent weight of the cube?.


Question: Cephalization refers to the development of what anatomical region, which evolved at the same time as bilateral symmetry in animals?
head
Head.