Which of the following is 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.

Explanation

To solve the question regarding the correct grouping of germinal layers and their corresponding organs or tissues, we can follow these steps:

### Step-by-Step Solution:

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

2. **Analyze Each Option**:
- **Option A**: Ectoderm - Retina, Epidermis, Nervous System
- All these structures originate from the ectoderm. Therefore, this option is correct.

- **Option B**: Mesoderm - Ovary, Urinary Bladder, Kidney
- The ovary and kidney are derived from the mesoderm, but the urinary bladder originates from the endoderm. Hence, this option is incorrect.

- **Option C**: Mesoderm - Kidney, Connective Tissue, Testis, Brain
- Kidney, connective tissue, and testis are mesodermal in origin, but the brain is derived from the ectoderm. Therefore, this option is incorrect.

- **Option D**: Endoderm - Thyroid, Pineal Gland, Thymus
- The thyroid and thymus are derived from the endoderm, but the pineal gland originates from the ectoderm. Thus, this option is also incorrect.

3. **Conclusion**:
- After analyzing all the options, we find that only **Option A** is correct, as all listed structures (retina, epidermis, nervous system) originate from the ectoderm.

### Final Answer:
The correct grouping is **Option A**: Ectoderm - Retina, Epidermis, Nervous System.

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