This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Vitamins and Minerals, Subject name: Biochemistry
Which of the following mineral can induce the synthesis of metallothionein? 
Select and explain. 
A. Zinc, B. Calcium, C. Iron, D. Phosphorous
A: Zinc
Answer: A: Zinc 
Explanation: Metallothioneins are a family of cysteine-rich, low molecular weight proteins localised to golgi apparatus. SH group of these proteins bind to physiological (copper and zinc) and xenobiotic metals (cadmium, mercury, silver, arsenic). Zinc and Cadmium induces the production of metallothionein -This propey is used in Wilson's disease as zinc reduces the intestinal absorption of copper by increasing the level of copper sequestering metallothionein.