Which one of the following elements is least likely to be found in commercial fertilisers?

Answer: Option D

Fertilizers typically provide, in varying proportions: (i) six macronutrients: nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and sulfur (S); and (ii) eight micronutrients: boron (B), chlorine (Cl), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), zinc (Zn) and nickel (Ni).