Introduction
The lining of the human intestine plays a crucial role in nutrient absorption and digestion. It is characterized by specialized structures that enhance its functionality.

Brush Border Structure
- The inner surface of the small intestine is lined with **microvilli**, which are tiny finger-like projections.
- These microvilli create a **"brush border"** appearance when viewed under a microscope.
- The brush border significantly increases the surface area available for absorption, allowing for more efficient nutrient uptake.

Cell Type and Function
- The epithelial lining of the intestine primarily consists of **simple columnar epithelium**, which is designed for absorption and secretion.
- Goblet cells, interspersed among the epithelial cells, secrete mucus that aids in the smooth passage of food and protects the intestinal lining.

Comparison with Other Options
- **Ciliated (Option B)**: Ciliated epithelium is typically found in the respiratory tract, where cilia help move mucus and trapped particles. It is not present in the intestinal lining.
- **Non-keratinised (Option C)**: While the intestinal lining is indeed non-keratinised, this does not specifically describe its absorptive characteristics. Non-keratinised epithelium is more common in areas requiring protection from abrasion, such as the esophagus.
- **Keratinised (Option D)**: Keratinised epithelium is found in areas exposed to friction and dehydration, like the skin. It is not suitable for the intestine, where absorption is key.

Conclusion
The brush border of the intestinal lining is essential for maximizing nutrient absorption, making option "A" the correct answer. Its specialized structure and function highlight the complexity of the digestive system in humans.