Word choice is used to get a point across. So if you look a choice A, the author definitely does not feel that the manufacturers are striving to provide COMPLETE information (or there wouldn't be the questions). I would say the same thing for D, making that an incorrect answer. Looking at B and C, the author does use exaggeration in personification, but he doesn't mention sales. He does however set a frustrated tone and touches on confusion of the customers, so I feel that C is the best answer here.
They can work hard to achieve the goal or do the action. Some people may in this way if they are under great deals of stress. They may lash out on people around them. By how they act to a subject.
Answer:
I think it's formal I always write them that way, so I would say formal.
Autocrat is your answer thank you :)
