Which of the following statements is not true regarding manganese? a. People who regularly take high amounts of iron and calcium supplements may have poor manganese status because these supplements inhibit manganese absorption. b. Manganese acts as a cofactor for many enzymes involved in the metabolism of carbohydrates, lipids, and amino acids. c. Manganese toxicity is more likely to occur from an excessive dietary intake than from exposure to a contaminated environment. d. Manganese absorption is inhibited by dietary phytates. e. Manganese toxicity symptoms include nervous system disorders.