Which germ layer forms CNS?

Explanation

**Step-by-Step Solution:**

1. **Identify the Germ Layers**: There are three primary germ layers in embryonic development: ectoderm, mesoderm, and endoderm.

2. **Understand the Ectoderm**: The ectoderm is the outermost germ layer. It is responsible for forming structures that are on the outer surface of the body.

3. **Functions of the Ectoderm**: The ectoderm forms the epidermis (the outer layer of skin) and the neural plates. The neural plates are crucial as they give rise to the nervous system.

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