Fill in the blank with the appropriate adverb from those given below :

I can _______ believe it. You are quite wrong.

hardly

The most appropriate adverb to fill in the blank is: Hardly

• Hardly emphasizes the difficulty in believing something. It suggests that it's almost impossible to accept the statement as true. This aligns perfectly with the sentence's sentiment of strong disagreement and disbelief.
• Hard simply means difficult or challenging. While it can be used with "believe," it lacks the same level of emphasis as "hardly" in expressing strong disbelief.
• Harded is not a grammatically correct adverb form.
• Hardlier is the comparative form of "hardly," but it wouldn't be used in this context.