Select the most appropriate ANTONYM of the given word. Innocuous

An antonym is a word whose meaning is the direct opposite of a given word. To identify it, first pin down the exact core meaning of the given word, then find the option whose meaning is the direct reversal of that meaning, not just any word carrying a different overall tone.

"Innocuous" means harmless — causing no injury, damage, or offence; something safe to be around. The direct opposite of "causing no harm" is "causing harm", so the antonym is the option that means harmful, injurious, or dangerous.

Checking each remaining option against this meaning-reversal:

• "Graceful" describes elegance or refinement in movement or manner — it concerns aesthetic quality, not the presence or absence of harm, so it does not reverse the meaning of "harmless".

• "Delightful" describes something highly pleasing or enjoyable — it concerns pleasure, not harm, so it is not a meaning-opposite of "harmless".

• "Powerful" describes great strength, force, or influence — a powerful thing, such as a powerful medicine, can still be entirely harmless, so strength is not the opposite of harmlessness.

Only the option expressing "causing harm" is the direct semantic reversal of "innocuous".