Cephalization is associated with

Options

A. radial symmetry
B. biradial symmetry
C. spherical symmetry
D. bilateral symmetry

Answer

### Step-by-Step Solution:

1. **Understanding Cephalization**: Cephalization is an evolutionary trend where the concentration of sensory organs, nerve ganglia, and the mouth occurs at one end of the organism, leading to the formation of a distinct head region.

2. **Characteristics of Cephalization**: This process is associated with the development of a head end, which allows for more efficient movement and interaction with the environment. It typically involves the presence of a centralized nervous system and sensory structures.

3. **Movement and Symmetry**: Cephalization is closely linked to bilateral symmetry, where the body can be divided into two mirror-image halves. This symmetry supports directional movement, which is advantageous for organisms in their habitat.

4. **Evaluating Options**:
- Option A: Radial symmetry – Incorrect, as cephalization is not associated with organisms that exhibit radial symmetry.
- Option B: Bilateral symmetry – Correct, as cephalization is primarily observed in bilaterally symmetrical organisms.
- Option C: Spherical symmetry – Incorrect, as this type of symmetry does not relate to cephalization.

5. **Conclusion**: The correct answer to the question "Cephalization is associated with" is **Bilateral symmetry**.