I think the answer would be medium
The most common nutrient deficiency in the world is Iron.
Iron is the answer.
Final answer:- a) Iron
Answer:
will form a precipitate of insoluble
when aqueous
is added.
Explanation:
According to solubility rule-
all carbonates are insoluble except group IA compounds and 
all salts of sodium are soluble
When
is added to given solutions, a double displacement reaction takes place in each solution to form a sodium salt and a carbonate salt.
So, in accordance with solubility rule, addition of
into
will result precipitation of insoluble 
Reaction: 