What digestive substances are bound to the microvilli of columnar epithelial cells of the small intestine?

It is the border brush enzyme.

Border brush enzymes are hydrolytic enzymes bound to the microvilli of columnar epithelial cells of the small intestines. They are produced by pancreas, and are ducted by main pancreatic duct. They are responsible for the final and terminal stage of digestion of dietary carbohydrates and proteins. They transport the resulting amino acids and sugars into the epithelial cells.

Mitochondria is the cell organelle that produced the energy that is needed in the body system in form of atp, that is why it is called the power house of the cell. energy is needed by the living organisms to carry out the activities which sustain life.  if the mitochondria is destroyed atp will not be produced. if the mitochondria is destroyed, energy production will stop and the affected living organism will not have the energy to carry out the necessary life processes; this will lead to the death of the organism.

The answer is a. i hope this