Which of the phrases given below the sentence should replace the phrase printed in bold type to make it grammatically correct? If the sentence is correct as it is, mark 'E' as the answer.
The drama had many scenes which were so humorous that it was hardly possible to keep a straight face.
hardly possible for keeping
hardly impossible for keeping
hardly impossible for keep
hardly possible keeping
No correction required
Correct answer is E
No explanation has been provided for this answer.