Garrod hypothesized that "inborn errors of metabolism" such as alkaptonuria occur because 21)

a. many metabolic enzymes use dna as a cofactor, and affected individuals have mutations that prevent their enzymes from interacting efficiently with dna.

b. metabolic enzymes require vitamin cofactors, and affected individuals have significant nutritional deficiencies.

c. enzymes are made of dna, and affected individuals lack dna polymerase.

d. genes dictate the production of specific enzymes, and affected individuals have genetic defects that cause them to lack certain enzymes.

e. certain metabolic reactions are carried out by ribozymes, and affected individuals lack key splicing factors.