SBI PO Prelims Model Paper 2

Directions (Q. 18 - 21): Which of the phrases (1), (2), (3) and (4) given below each sentence should replace the phrase printed in bold in the sentence to make it grammatically correct? If the sentence is correct as it is given and 'No correction is required', mark (5) as the answer

He was so tired that he could barely keeping his eyes open while driving.