I would say because it is hard to remember. Unless each one of those stands for a world, kind of like an acronym, then good luck remembering it!
Answer:
This is the second question like this I've seen. They aren't the greatest.
Explanation:
The question is not good. The answer would be option a, Transport even though it doesn't make a whole lot of sense when you really go into detail.
It could also be option d, Application but I think they're going for the first.
