Combine the following sentences into one grammatically correct complex sentence: The car broke down. We were driving on the highway.
Correct: B
Option B uses the subordinating conjunction 'when' to effectively combine the two ideas, indicating that the car broke down *while* they were driving on the highway. This creates a complex sentence with a main clause and a subordinate clause indicating time. Option A creates a compound sentence, option C uses a semicolon correctly but doesn't show the temporal relationship as clearly as B, and option D creates a dangling modifier, suggesting the car was driving.