True horns are always

Options

A. hollow
B. arise from frontal bones
C. never shed
D. all correct

Answer

To answer the question "True horns are always," we need to analyze the characteristics of true horns based on the provided information.

### Step-by-Step Solution:

1. **Understanding True Horns**:
- True horns are permanent pointed projections found on the heads of certain mammals, particularly ruminant artiodactyls like cattle, goats, and antelopes.

2. **Characteristics of True Horns**:
- **Hollow Structure**: True horns have a hollow space between the keratin sheath and the core of live bone. This means that they are indeed hollow.
- **Origin**: True horns arise from the frontal bones of the skull. This is a critical point as it indicates their anatomical structure.
- **Permanence**: True horns are permanent structures; they are present from birth and do not shed throughout the animal's life. This distinguishes them from antlers, which do shed.

3. **Evaluating the Options**:
- **Option A (Hollow)**: True horns are hollow due to the space between the keratin sheath and the bone.
- **Option B (Arise from Frontal Bones)**: True horns do arise from the frontal bones of the skull.
- **Option C (Never Shed)**: True horns are permanent and do not shed.
- **Option D (All Correct)**: Since all the previous statements are true, this option is also correct.

4. **Conclusion**:
- Since all the characteristics mentioned (hollow, arise from frontal bones, and never shed) are true for true horns, the correct answer is **Option D: All correct**.

### Final Answer:
**Option D: All correct**

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