Final answer:
The flattening of the small intestine lining would lead to decreased nutrient absorption due to the significant reduction in surface area caused by the loss of the structure of villi and microvilli.
Step-by-step explanation:
If the lining of the small intestine became flattened, the likely consequence would be b) Decreased absorption of nutrients. This is because the villi and microvilli, which are folds and small projections respectively, greatly increase the surface area of the small intestine, facilitating the absorption of nutrients. Without the villi and microvilli, the available surface for nutrient absorption would be significantly reduced, leading to decreased efficiency in nutrient uptake into the bloodstream.
It is important to understand that villi and microvilli are critical to the proper functioning of the small intestine. They do not simply passively exist; they actively engage in the absorption process. When these structures are damaged or flattened, conditions such as malabsorption syndromes can result, which affect the body's ability to absorb vitamins, minerals, and other nutrients from food.