A car is third person singular, so it would have to be "A car causes a traffic jam on a busy thoroughfare." This is in the present tense. If we used plural, cars, we could say "Cars have caused a traffic jam on a busy thoroughfare." Otherwise it would have to be "A car has caused a traffic jam on a busy thoroughfare." These are both in the past. But C), caused is correct and in the past tense.

caused

caused