The purpose of the digestive system is to break down food into simple molecules that the cells of the body can use.
Food is broken down into its simplest units called monomers. Proteins are broken down into amino acids, fats are broken down into fatty acids and glycerol while carbohydrates are broken down into glucose units.
Glucose is taken in by the cells of the body and through the process of cellular respiration is used to produce the ATP, the form of energy that cells use. Cellular respiration is the process by which cells use glucose to produce energy to power their functions.
The connective tissue is among the four major classes of the tissue. It is the most widely distributed and the most abundant class of the tissues. However, the type of tissue in every organ varies. Composed of cells, fibers and matrix, this type of tissue is different in different organs of the body.
The variability in it's type is provided by the difference in the degree of the order of the cells, fibers, and the matrix. This variability contributes to the diversity of this tissue.
Hence, the blank can be filled with 'diversity'.
A diverse set of ecosystems means that there will be a wide variety of selection pressures exerted on the organisms. Therefore, natural selection will act to bring out the best suited traits for that particular ecosystem. The more the ecosystems are diverse, the more will be the difference between the traits between the organisms that will survive. This means that the biodiversity will increase.
I think the best answer is D.
I think it brings to the warm places cold air and to cold places it brings warm air