Thanks for the question! It’s good to anticipate what the answer might be, but don’t get too hung up on it, stay flexible! Here, the answer as you now know did not have to do with fuel. You’re looking for something that strengthens the argument. And the argument argues that reducing the speed limit saved lives. So you want something that makes that seem more likely. (D) directly says that fatality rates is higher when you’re going faster than 55. That’s pretty direct evidence for the conclusion and so strengthens it.
Hope this helps! Feel free to ask any other questions that you might have.
