Lipids and carbohydrates differ in which of the following fundamental respects?

Carbohydrates are hydrophilic  whereas Lipids are hydrophobic.

Explanation:

Carbohydrates can be most commonly understood as hydrates of carbons. They generally contain more than two carbon atoms and are easily soluble in water, thus giving them the characteristics of hydrophilic compounds. Sugar and glucose are some of the important examples of carbohydrates.

On the other hand, lipids comprise a polar region, which attracts water and a much larger non-polar region, which repels water. This non-polar region dominates the polar region of lipid molecules thus making it a hydrophobic compound. Oils, fatty substances, steroids, and waxes are some of the important examples of Lipid molecules.

i think that c)gold was found there

but i am not sure

answer: substrate concentration. enzymes work best when there is a high enough substrate concentration for the reaction they catalyse.