Fat is completely digested in the

The correct answer is: A. Small intestine.

Fat is digested in the small intestine by bile, which is a fluid produced by the liver. Bile helps to break down fat into smaller molecules that can be absorbed by the body. The small intestine is also lined with cells that have special receptors that can absorb these smaller molecules.

The mouth is not involved in the digestion of fat. The stomach does produce some enzymes that can break down fat, but the majority of fat digestion occurs in the small intestine. The large intestine is responsible for absorbing water and electrolytes from the digestive tract, and it does not play a role in the digestion of fat.