Which of the following is not the correct grouping?

Options

A. Ectoderm-Retina, epidermis and nervous system
B. Mesoderm-Ovary, urinary bladder and kidneys
C. Mesoderm-kidneys, connective tissue and testis
D. Endoderm-Thyroid, pineal and thymus.

Answer

To solve the question regarding which grouping is not correct, we will analyze each option based on the embryonic germ layers: ectoderm, mesoderm, and endoderm.

### Step-by-Step Solution:

1. **Understand the Germ Layers**:
- The three primary germ layers in embryonic development are ectoderm, mesoderm, and endoderm. Each layer gives rise to specific organs and tissues in the body.

2. **Evaluate Option 1**:
- **Option 1** states: "Retina, epidermis, and nervous system are ectodermal in origin."
- **Analysis**: The retina, epidermis, and nervous system all originate from the ectoderm.
- **Conclusion**: This option is correct.

3. **Evaluate Option 2**:
- **Option 2** states: "Ovary, urinary bladder, and kidneys are mesodermal in origin."
- **Analysis**: The ovary and kidneys arise from the mesoderm, but the urinary bladder is actually derived from the endoderm.
- **Conclusion**: This option is incorrect.

4. **Evaluate Option 3**:
- **Option 3** states: "Kidneys, connective tissue, and testes are mesodermal in origin."
- **Analysis**: All these structures (kidneys, connective tissue, and testes) arise from the mesoderm.
- **Conclusion**: This option is correct.

5. **Evaluate Option 4**:
- **Option 4** states: "Pineal gland is ectodermal in origin."
- **Analysis**: The pineal gland is indeed derived from the ectoderm.
- **Conclusion**: This option is correct.

6. **Final Conclusion**:
- The incorrect grouping is found in **Option 2**, as it incorrectly categorizes the urinary bladder as mesodermal in origin.

### Final Answer:
The option that is not the correct grouping is **Option 2**: "Ovary, urinary bladder, and kidneys are mesodermal in origin."

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