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A. Increasing surface area to improve nutrient absorption between the digestive and the circulatory systems.

Explanation:

Our intestines, on the inside, are lined with the intestinal mucosa. This mucosa is not straightened, as it might seem macroscopically; it rather has this wavy appearance forming folds. Also, epithelial cells in this mucosal layer have lots of small finger-like extensions called the villi.

Folds and villi increase the contact surface between the nutrients in the lumen and mucosa, thus increasing the rate of absorption of these nutrients between the intestines and the blood vessels below the epithelium.

i'm gonna put a couple so you can chose from

explanation:

if you know the fur color of the offspring mice, you can use the ratios to identify the genotypes of the parents.

if either parent mouse passes a dominant allele, the offspring will have black fur.

if the parental mice has two different fur color (i.e white and black) , the color of the offspring's fur would be either black, white, or the combination of both (grey)

hope this : )

unicellular organisms, like bacteria, are able to perform all life functions within one single cell. multicellular organisms need many different types of cells to carry out the same life processes. each of these special types of cells has a different structure that it perform a specific function.