In the following question, out of the four alternatives, select the alternative which will improve the underlined part of the sentence. In case no improvement is needed, select “No improvement”. A young taxi driver has claimed that a monster attacked him while he drove along a lonely road?

Option 3 : while he was driving

The correct answer is option 3 i.e while he was driving. 

• The given sentence talks about a past continuous action. 
• That is he was attacked by the monster when he was engaging in the continuous action of driving. 
• We should use the present participle form of the verb (ing) to denote continuous actions.
• We use the auxiliary verb was to denote past tense. 
• Hence the correct answer will be while he was driving.

Thus, the improved sentence will be - "A young taxi driver has claimed that a monster attacked him while he was driving along a lonely road."