All these (D).
When you ask for an opinion on a particular topic, you are expected to give your position, but still, to build arguments to support your opinion. In this case, the person must say whether or not he is in favor of raising the age to drive for 18 years, but must describe and explain his point of view.
For example: I am in favor of increasing the age to drive. I think so because I think people under 18 still do not have the maturity to handle the direction.