The toxicity of zinc in soil is reduced by adding

Answer: Option A

The toxicity of zinc in the soil is reduced by adding superphosphate.
Superphosphate is a component of fertilizer that primarily consists of monocalcium phosphate, Ca(H₂PO₄)₂.
Superphosphate or Super provides calcium, phosphorus and sulphur to promote legume growth and increase nitrogen fixation symbiotically from the atmosphere.
Phosphorus inhibits the availability of zinc for absorption in soil, thus, zinc toxicity is reduced by adding superphosphate.