Correct Answer - Option 2 :
Fertilizers required for crop production includes nitrogen as one of their ingredients
The given statement is very simple and clear, now.
1 is correct and directly related to the given statement but is not its effect.
2 is correct, fertilizers include nitrogen but nitrogen is available in all fertilizers of every country but not all type of soil is deficient in nitrogen, so it is correct but it is not the effect of the given statement.
3 it is correct, is related to the statement and is also its effect, excessive nitrogen present in water is harmful so this statement is correct and the effect of the given statement.
4 is incorrect because the majority of crops require nitrogen but not all crops do.