This is an opportunity for you to show that you understand the company's support organization and how it relates to the rest of the company. Support is a good way to join an organization, learn the product and over time move your career to other customer or product related functions.

It is OK to say that you want to grow your skills in support, and then move to another area of the company where you can add the most value. Don't seem overly eager to leave, rather that you would want to move up/out once you can provide greater value to the company in another role