Which primary germ layer forms liver, pancreas, etc.?

Explanation

**Step-by-Step Solution:**

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

2. **Understand the Function of Each Germ Layer**:
- **Ectoderm**: This is the outermost layer and is responsible for forming external structures such as the epidermis (skin) and the nervous system.
- **Mesoderm**: This middle layer forms structures such as muscles, blood vessels, and other connective tissues.
- **Endoderm**: This is the innermost layer and is responsible for forming internal organs.
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