Complete the polite vampire's diary entry by selecting the grammatically correct phrase.

I felt terribly guilty when I arrived at Count Vlad's castle carrying three extra velvet capes as a gift. He warmly assured me that I ______ them, as his closet was already bursting with capes.

The correct answer is needn't have brought.

When reporting needn't have + past participle (which expresses that an action was performed but was entirely unnecessary), the modal phrase remains unchanged in indirect speech.

If you chose "didn't need to bring," it changes the meaning! "Didn't need to" implies the action wasn't necessary and therefore probably didn't happen. Since the vampire did bring the capes, "needn't have brought" is the only accurate choice.