Most common zinc fertiliser is

Answer: Option C

Zinc sulphate is the most commonly used zinc fertilizer worldwide.
It is a micronutrient fertilizer and it usually contains 33% zinc and 15% of Sulphur. It is available in both crystalline monohydrate and heptahydrate forms.
It helps to prevent low yields, spotted leaves and stunted growth. It can also be used as a natural fungicide.