Explanation:

- The original sentence uses "how bad," which describes an adjective. However, "wanted" requires an adverb to describe how intensely or strongly you wanted something.

- Option 1: how badly

- This is the correct choice. "Badly" is an adverb that modifies "wanted," indicating the degree of desire.

- Correct Answer

- Option 2: what bad

- The phrase "what bad" is not a grammatically correct substitution here.

- Option 3: No improvement required

- The original sentence incorrectly uses "how bad" as it fails to use an adverb.

- Option 4: badly how

- This ordering is incorrect; it disrupts the structure of the sentence.