I'd say D. expert power because expert power is when an employee ( or in your case the teacher) has a high set of knowledge/skills that other employees do not posses. Which by the information above about this teacher's PhD and thier experience, I assume that this teacher must have expert power.
The answer to your question is BOTH A AND B
They add different things to the car so that they can make the cars faster so they can go onto the market they also make the car more expensive so they can make more money. Don't know if that helps but there.
