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:đ If + had + past participle, ⊠would have + past participleHere:âwould have succeededâ shows past unreal result.So the correct form in the if-clause is had worked. Read more in App