Correct option is B
The correct antonym of the word "Innocuous" is "Harmful."
Innocuous means not harmful, inoffensive, or harmless.
Hindi Meaning: हानिरहित या निर्दोष।
Synonyms: Harmless, Inoffensive, Safe, Benign.
Antonyms: Harmful, Dangerous, Toxic, Malignant.
Harmless means not causing or capable of causing damage.
Example: The prank was completely harmless.
Harmful means causing or likely to cause harm or damage.
Example: Smoking is harmful to health.
New means recently created or discovered.
Example: She bought a new dress for the party.
Old means having existed for a long time.
Example: The building is very old and historic.