Despite _____ hard, he failed the exam.

Studying

Studied

He studied

None of these

"Despite" is followed by a gerund (verb + ing), so "studying" is correct.

The correct sentence is: "Despite studying hard, he failed the exam."

سخت مطالعہ کرنے کے باوجود ، وہ امتحان میں ناکام رہا۔