Answer
b.
Work Step by Step
Option a. is incorrect. Fertilization is the process by which two haploid gametes unite to form a single diploid cell called a zygote.
Option c. is incorrect. Symmetry is how the parts of the body are distributed along an axis.
Option d. is incorrect. Multicellularity is the term used to describe an organism made of more than one cell.
Option b. is correct. Cephalization is the congregation of nerve cells and sensory organs at the anterior portion of an organism.