Option 1 -> Includes Chlorine (A), which IS diatomic (Cl₂), making this incorrect.
Option 2 -> Includes Chlorine (A), which IS diatomic (Cl₂), making this incorrect.
Option 3 -> Includes Chlorine (A), which IS diatomic (Cl₂), making this incorrect.
Option 4 -> Lists only Argon, Sulphur, and Helium - all are NOT diatomic, making this correct.
Hence, Option 4: (B), (C) and (D) only -> Chlorine exists as Cl₂ (diatomic), while Argon and Helium are noble gases existing as single atoms (Ar, He), and Sulphur exists as S₈ molecules at room temperature. Only (B), (C), and (D) are NOT diatomic -> correct