Final answer:
The sentence should be completed using the word 'drove', as it correctly implies the action of driving in the past tense, which was occurring at the time of the car crash.
Step-by-step explanation:
The sentence "Atul ________ very fast when the car crashed" requires a verb in the past tense to indicate an action that was occurring at the time the car crashed. The correct option to complete the sentence is b) drove, which is the past tense of the verb drive. So, the complete sentence should read: "Atul drove very fast when the car crashed." This indicates that Atul was in the act of driving quickly at the moment when the incident occurred.