This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous, Subject name: Medicine
Anion-gap Metabolism with decreased vision occurs with the following poisoning 
Select and explain. 
A. Cadmium, B. Mercury, C. Ethanol, D. Methanol
D: Methanol
Answer: D: Methanol 
Explanation: (D) Methanol# Acute intoxication with Methanol is common in chronic alcoholics.> Headache, vertigo, vomiting, abdominal pain, dyspnea, blurred vision, and hyperemia of the optic disc can occur.> Visual disturbances are caused by damage to retinal cells and the optic nerve by methanol metabolites.> Severe cases of intoxication can lead to blindness.> Other symptoms include bradycardia, prolonged coma, seizures, acidosis, and death by respiratory depression.> Because methanol is biotransformed by alcohol and aldehyde dehydrogenase to highly toxic products (formaldehyde & formic acid, respectively), Ethanol, which has a high affinity for the enzyme, is useful in therapy because it reduces the biotransformation of methanol.> Other treatments include hemodialysisto enhance removal of methanol & its products and alkalinization to reverse metabolic acidosis> 4-methylprazole, an inhibitor of alcohol dehydrogenase, has also been proposed for treatment.> Treatment with ascorbic acid would aggravate the acidosis.