Answer: D, The elements that can function as inorganic coenzymes are iron, magnesium, and zinc. In fact, all three are essential for the functioning of biologically important enzymes.
Key Takeaway: Inorganic coenzymes typically cannot be made by the body and must be supplied through the diet. Inorganic coenzymes are typically metallic, and other examples include manganese, copper, and selenium. Important enzymes requiring inorganic coenzymes include glucose-6-phosphatase, DNA polymerase, and catalase. Inorganic coenzymes are not to be confused with other elements such as calcium and iodine are essential for biological functions but do not act to activate enzyme activity.