Explanation:

- Your Original Sentence: "She doesn't hesitate to do whatever her husband (does)."

- Option 1: would do - Suggests a hypothetical situation and implies she might act similarly in imagined scenarios. It shifts the meaning from present actions.

- Option 2: did - Refers to past actions, which changes the sentence to indicate she follows her husband's previous actions, not current ones.

- Option 3: shall do - Implies future actions, suggesting she will follow whatever her husband decides in the future. Not suitable for current actions.

- Option 4: no improvement - The original sentence is clear and correct as it is, reflecting current actions her husband takes.

The best choice is Option 4: no improvement.

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