Which of these is a risk of speeding a. longer braking distance b. greater likelihood of being distracted c. tire damage d. mechanical failure

The answer should be A.
The faster you are going the more force will be added, as you brake you will feel about double the mass of the car causing longer braking distance.

I would say the answer would be D. Because tire damage can possibly make you slower, longer breaking distance means you will be on your breaks for a long period of time, and mechanical failure will just have you pull over because you are so worried or you car won't work. So the answer is D.