I bought bread; we already had some.

  1. shouldn't
  2. couldn't
  3. needn't have
  4. mustn't have
Answer

C) needn't have

Did it, but it was unnecessary – "needn't have + V3". Modals, Conditionals & Verb Forms · Modals

English MCQ · More English: Modals, Conditionals & Verb Forms MCQs · Practise