Explanation:

- The word "blunt" typically means something that is not sharp, or lacking a point or edge. It can also mean straightforward or direct in communication, without trying to be subtle or polite.

- Option 1: Lengthy – This means extending for a long distance or time; not the opposite of blunt.

- Option 2: Sharp – This means having an edge or point that is able to cut or pierce. It's the direct opposite of blunt, which indicates dullness.

- Option 3: Large – This refers to size, not related to being blunt or sharp.

- Option 4: Charred – This refers to being burned or scorched, and doesn’t relate to the sharpness of an object.

- Option 2: Sharp is indeed the correct antonym for "blunt."