Unique to the brain of mammals

Options

A. 3 meninges
B. 4 optic lobes
C. Gyri and Sulci
D. All the above

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks for a feature that is unique to the brain of mammals. We need to analyze the given options to find the correct answer.

2. **Analyzing the Options**:
- **Option A: Three Meninges**: The three meninges are the Pia mater, Arachnoid, and Dura mater. While the Dura mater is unique to mammals, the other two (Pia mater and Arachnoid) are present in many other animals as well. Therefore, this option is not unique to mammals.

- **Option B: Four Optic Lobes**: Mammals have two pairs of optic lobes, which means they have a total of four lobes. However, this feature is not unique to mammals; for example, cephalopods like octopuses also have four optic lobes. Thus, this option is incorrect.

- **Option C: Gyri and Sulci**: Gyri (ridges) and Sulci (furrows) are unique structures found in the brains of mammals. These structures increase the surface area of the brain and are distinctive features that separate mammalian brains from those of other animals. This option is likely the correct answer.

- **Option D: None of the Above**: This option would imply that none of the previous options are unique to mammals, but since we have identified Gyri and Sulci as unique, this option can be eliminated.

3. **Conclusion**: After analyzing all the options, the unique feature of the brain of mammals is **Gyri and Sulci**. Therefore, the correct answer is **Option C**.

### Final Answer:
**Option C: Gyri and Sulci**

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