Answer:
Why was the cost of an automobile so expensive?
So by logic you could cross out the second choice, along with the last one. And from doing my research, I believe that it was because "It cost to pay all the assembly line workers." If I am not correct, I am sorry, but I don't know what time period this "automobile" was made in. If you're talking about something in the 1800's and the automobile was made overseas, then the last answer could also be valid, because the government did charge high tariffs.