Which of the Following Statements Correctly Describes Archibald Garrod's (1902)

Which of the following statements correctly describes Archibald Garrod's (1902) hypothesis for how "inborn errors of metabolism" such as alkaptonuria occur?

A) Metabolic enzymes require vitamin cofactors, and affected individuals have significant nutritional deficiencies.
B) Enzymes are made of DNA, and affected individuals lack DNA polymerase.
C) Certain metabolic reactions are carried out by ribozymes, and affected individuals lack key splicing factors.
D) Genes dictate the production of specific enzymes, and affected individuals have genetic defects that cause them to lack certain enzymes.