If I had won a million, I _____ a started a business of my own.*had startedwill startwould have startedwould had started

To determine the correct option for the sentence "If I had won a million, I _____ a started a business of my own.", we need to analyze the structure of the conditional sentence.

1. Understanding Conditional Sentences: The given sentence is in the past unreal conditional structure, which typically uses "if + past perfect, would have + past participle."

2. Choices Breakdown:

   • had started: This form is in the past perfect. It's not appropriate for the main clause following "if" in this case.
   • will start: This form is future simple. It's not suitable since the "if" clause indicates a hypothetical situation in the past.
   • would have started: This is the correct form. It properly indicates an unreal situation in the past, showing that the action of starting a business didn't actually happen because the condition wasn’t met.
   • would had started: This form is incorrect as it mixes conditional past with the past perfect incorrectly.

Final Answer

The correct option is "would have started." Hence, the complete sentence reads: "If I had won a million, I would have started a business of my own."