Step 1: Compute N percent by formula: ammonium sulphate is about 21 percent.
Step 2: Ammonium chloride is about 25 percent, calcium ammonium nitrate about 26 percent (diluted by carbonate filler).
Step 3: Ammonium nitrate has two N atoms per formula unit, giving about 34 percent, the highest.
Step 4: Increasing order is (A), (C), (D), (B), matching the fourth option.