A.
The correct answer is sugar molecules.
The carbohydrates are the polymers of the sugar molecules. The carbohydrate is broken down into simple sugars, in case, the breaking down of the carbohydrates does not take place, the sugar molecules would not be available for the production of the energy.
B.
The correct answer is amino acids.
the proteins are the polymers of the amino acids. In case, the enzyme for the digestion of the protein is absent then it cannot be broken down into amino acids, and the amino acids cannot be absorbed by the body.
So, the blank A can be filled with sugar molecules and the blank B can be filled with amino acids.