Option 1 → Incorrectly matches Oxygen with 12 u (should be 16 u) and Carbon with 23 u (should be 12 u).
Option 2 → Incorrectly matches Oxygen with 23 u and Calcium with 16 u (reversed values).
Option 3 → Incorrectly matches Oxygen with 12 u and Carbon with 16 u (values are swapped).
Option 4 → Correctly matches: Oxygen (16 u), Carbon (12 u), Calcium (40 u), and Sodium (23 u).
Hence, Option 4: (A) - (III), (B) - (I), (C) - (IV), (D) - (II) → These are the standard atomic masses for these elements: Oxygen has atomic mass 16 u, Carbon 12 u, Calcium 40 u, and Sodium 23 u → correct