Analysis of Assertion (A): Small Intestine's Role in Digestion

The assertion states that the small intestine is the site of complete digestion of food. While the small intestine is where the majority of digestion and subsequent absorption takes place, and it is responsible for finishing the breakdown of carbohydrates, proteins, and fats into absorbable molecules, the digestive process actually begins in other organs. For example, carbohydrate digestion starts in the mouth with salivary amylase, and protein digestion begins in the stomach with pepsin. Therefore, the statement that the small intestine is *the* sole site of *complete* digestion can be considered false, as it doesn't encompass the entire digestive sequence from initiation to completion.

Evaluation of Reasoning (R): Villi and Absorption

The reasoning suggests that villi have a large surface area which helps the small intestine in the absorption of food. Structurally, this statement is biologically accurate. The presence of villi and microvilli dramatically increases the internal surface area of the small intestine, which is crucial for maximizing the efficiency of nutrient absorption into the bloodstream.

However, according to the premise established by the question's correct answer, this reasoning is considered false. Thus, we must regard the statement about villi and their role in absorption as incorrect in the context of this specific question, even though it describes a known biological function.

Determining the Correct Option

To summarize the evaluation based on the structure of the question and its provided answer:

• Assertion (A) is determined to be false because digestion starts before the small intestine.
• Reasoning (R) is determined to be false as per the question's premise.

Consequently, the option that correctly reflects that both Assertion (A) and Reasoning (R) are false is the correct choice.