I think a good way to approach these questions is to try to imagine someone is speaking it to you and anticipate the answer choice. Don't try evaluate each answer choice on its own merit. If anything, be proactive in that search.
Here, they are comparing learning theory vs practical use of statistics and learning to build vs learning to drive a car. Just as ordinary drivers don't need to know how to build a car, then they don't need to know the theory of statistics. That's the point of the argument based on the way it was structured and that's the answer we should be looking for. This is answer choice D.
Answer choice C is incorrect because it is specifically focusing on what teachers should do and comparing relative importance of skills. This would be right if the passage was going down the line of saying that driving instructors should teach only the driving skills that are of most importance to ordinary drivers. It takes on a different focus than the passage is really trying to get at.
I hope this helps, but please let me know if there is anything else you'd like me to add!