Brush border columnar epithelium present in
A. Proximal convoluted tubule
B. Ventricle of brain
C. Bronchi and bronchioles
D. Small intestine

Hint: Epithelial tissues can be found all through the body. They structure the covering of all body surfaces, line body cavities, and empty organs, and are the significant tissue in organs. They play out several functions that incorporate assurance, emission, assimilation, discharge, filtration, dissemination, and sensory reception.

Complete answer:
A brush border is the microvilli-made surface of essential cuboidal and fundamental columnar epithelium found in different areas of the body. Since individual microvilli are so little and are firmly pressed in the brush fringe, individual microvilli must be viewed using an electron magnifying lens.
Brush border cells are found primarily in the:
The small intestine plot: This is the place absorption happens. The brush borders of the intestinal covering are the site of terminal starch absorptions. The microvilli that include the brush border have impetuses for this last part of assimilation secured into their apical plasma layer as essential membrane proteins.
These compounds are found close to the carriers that will at that point permit assimilation of the processed supplements.
Hence, Option (4) Small intestine is a correct answer.

Additional Information:
The proximal convoluted tubule is liable for the reabsorption of all the filtered substances such as sodium, amino acids, and reabsorbs around 67% of each secluded substance.
The ventricular arrangement of the brain is answerable for the creation, transport, and expulsion of cerebrospinal liquid, which washes the focal sensory system.
The bronchi and bronchioles are portions of the 'Conduction Zone' of the respiratory framework - permitting the entry of air from the outside climate into the lungs where vaporous trade can occur.

Note:
A brush border epithelium is a columnar epithelium that is secured with microvilli that are protoplasmic augmentations of the cell on the uncovered surface. Such a sort of epithelium is found in the small intestine and aids in absorption. They contain a few catalysts present in the apical plasma layer as necessary membrane proteins for assimilation that is found close to the carriers and permits absorption of the processed supplements.