If I ____________ harder, I would have succeeded.AworkBworkedChad workedDhave workedAnswer: C. had worked Read Explanation: The sentence is a third conditional sentence (past unreal condition).Structure of third conditional:👉 If + had + past participle, … would have + past participleHere:“would have succeeded” shows past unreal result.So the correct form in the if-clause is had worked. Read more in App